A wide-band ultraviolet detection objective with a large field of view

Abstract

This invention relates to a wide-band ultraviolet (UV) inspection objective, belonging to the field of optical instrument technology. To address the challenge of achieving a balance between short wavelength, large numerical aperture, large field of view, and wide-band detection in existing technologies, while simultaneously considering system complexity and manufacturing cost, this invention proposes a wide-band UV inspection objective comprising a first mirror group, a second mirror group, a third mirror group, and a fourth mirror group arranged coaxially from the object plane. Each mirror group contains several lenses, wherein the first and fourth mirror groups are variable mirror groups. This invention features shorter wavelength, wider band, larger numerical aperture, and larger field of view, simultaneously meeting high requirements for resolution, detection range, and detection efficiency, and is suitable for defect detection and quality control in the semiconductor wafer manufacturing field.

Description

Technical Field

[0001] This invention belongs to the field of optical instrument technology, specifically relating to a wide-band ultraviolet detection objective lens with a large field of view. Background Technology

[0002] In the semiconductor manufacturing industry, wafer fabrication is a costly process. To effectively control costs and improve yield, timely and accurate detection of defects such as particles, scratches, and pattern deviations on wafers is crucial. Traditional defect detection systems mostly use short ultraviolet single-wavelength detection. While short wavelengths improve system resolution, different types of defects have varying sensitivities to different wavelengths, making single-wavelength detection insufficient to comprehensively and effectively identify all defects. This necessitates the development of an inspection objective that can cover a wider wavelength range. Furthermore, as semiconductor devices continue to shrink in size, higher demands are placed on the resolution of the detection system. Based on the resolution calculation formula for optical microscopy systems… Shorter wavelengths ( ) and larger numerical aperture ( Improving resolution is crucial. However, existing technologies struggle to achieve both high resolution and wide field of view and broad band detection simultaneously, which remains a pressing technical challenge.

[0003] To address the aforementioned technical bottlenecks, existing technologies have proposed several solutions. For example, Chinese patent document CN118732248A discloses a microscope objective optical system that employs a catadioptric structure, aiming to overcome the difficulty of simultaneously achieving a large numerical aperture and a large field of view, thus enabling the realization of numerical aperture... Achieving a field of view of 0.9 nm and a maximum of 1 mm, this patent also proposes that all optical element surfaces be spherical to reduce manufacturing difficulty. Another Chinese patent document, CN120065493A, provides a large field of view, large numerical aperture ultraviolet broadband microscopy optical system. This system includes a complex optical structure comprising a microscope objective, a relay system, and an imaging tube, successfully achieving broadband chromatic aberration correction from 250 nm to 500 nm. Its numerical aperture... It is greater than or equal to 0.9, and the field of view is greater than or equal to 1mm. It can even be increased to more than 2mm with the help of a magnifying optical system.

[0004] However, these existing technologies still have some shortcomings. Although patent document CN118732248A made improvements in numerical aperture and field of view, it did not explicitly mention effective coverage capability in the ultraviolet wideband, which is a limitation for the semiconductor industry, which needs to sensitively detect a variety of defects. While patent document CN120065493A solved the problem of the ultraviolet wideband, it uses a complete optical system consisting of a microscope objective, a relay system, and an imaging tube, with a complex overall structure and a large number of components, which undoubtedly increases the difficulty and cost of system design, manufacturing, and assembly.

[0005] Therefore, this invention aims to provide a more compact and streamlined solution: a single ultraviolet wide-band, large-field-of-view inspection objective. This objective aims to optimize three key performance indicators—short wavelength, wide band, large numerical aperture, and large field of view—while avoiding reliance on complex relay systems. Through a unique lens group design, this invention effectively resolves the inherent trade-off between high resolution, large field of view, and wide band in existing technologies. This significantly improves the comprehensiveness and efficiency of semiconductor wafer defect detection while reducing system complexity and manufacturing costs. Summary of the Invention

[0006] To address the challenge of achieving a balance between short wavelength, large numerical aperture, large field of view, and wide-band detection in existing technologies, while also considering system complexity and manufacturing cost, this invention proposes the following solution:

[0007] A wide-band ultraviolet detection objective lens, the detection objective lens comprising a first lens group G1, a second lens group G2, a third lens group G3 and a fourth lens group G4 arranged coaxially from the object plane;

[0008] The second lens group G2 includes a first biconvex lens 4, a biconcave lens 5, and a first plano-convex lens 6;

[0009] The third lens group G3 includes a second meniscus lens 7 and a second biconvex lens 8.

[0010] Furthermore, the first mirror group G1 includes a first lens 1, a first meniscus lens 2, and a spherical reflector 3 arranged coaxially from the object plane.

[0011] The fourth lens group G4 includes a third meniscus lens 10, a third biconvex lens 11, a fourth meniscus lens 12, a fifth meniscus lens 13, and a fourth biconvex lens 14, which are arranged coaxially from the third lens group G3.

[0012] Furthermore, the first lens group G1 includes a first lens 1, a first meniscus lens 2, and a second lens 31 arranged coaxially from the object plane.

[0013] The fourth lens group G4 includes a sixth meniscus lens 101, a second plano-convex lens 111, a fourth meniscus lens 12, a fifth meniscus lens 13, and a seventh meniscus lens 141, which are arranged coaxially from the third lens group G3.

[0014] Furthermore, the second biconvex lens 8 is a thick lens with an aspect ratio greater than 0.83.

[0015] Furthermore, the bending direction of the first meniscus lens 2 is the same as the bending direction of the spherical reflector 3.

[0016] Furthermore, the ball-shaped reflector 3 has a central opening, the area of ​​which accounts for 5-25% of the surface area of ​​the ball-shaped reflector 3.

[0017] Furthermore, an aperture stop 9 is provided between the third mirror group G3 and the fourth mirror group G4.

[0018] Furthermore, the second lens 31 has a light-passing hole at its center, the light-passing hole is coated with an anti-reflection film, and a reflective film is coated outside the range of the anti-reflection film. The width of the transition area between the anti-reflection film and the reflective film is less than 0.1 mm.

[0019] Furthermore, the first lens 1 has a light-transmitting hole at its center, the light-transmitting hole is coated with an anti-reflective film, and a reflective film is coated outside the area of ​​the anti-reflective film. The width of the transition area between the anti-reflective film and the reflective film is less than 0.1 mm.

[0020] Furthermore, the first lens 1 can be any one of a biconvex lens, a plano-convex lens, or a meniscus lens.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The ultraviolet wide-band, large-field-of-view inspection objective described in this invention achieves a breakthrough in spectral coverage and resolution. By employing a cleverly combined catadioptric-reflective hybrid structure using a spherical reflector and multiple lens elements, this inspection objective achieves ultra-wide ultraviolet imaging from 255nm to 465nm, effectively correcting chromatic aberration and ensuring excellent imaging quality for different wavelengths of light. This not only far exceeds the spectral range of existing technologies above 320nm, but also fully utilizes the sensitivity of different wavelengths of light to different defects, greatly improving the ability to identify various defects such as particles, scratches, and pattern deviations. Simultaneously, its shorter cutoff wavelength directly results in higher optical resolution, enabling the clear capture of even the smallest defect details.

[0023] 2. The ultraviolet wide-band large field-of-view inspection objective lens described in this invention effectively solves the problem of balancing a large numerical aperture and a large field of view. In traditional designs, increasing the numerical aperture to improve resolution often leads to a sharp reduction in the field of view, limiting inspection efficiency. This invention optimizes the parameter configuration of the first, second, third, and fourth lens groups, and sets an aperture stop between the third and fourth lens groups, enabling the objective lens to maintain a large imaging target area while achieving a high numerical aperture. The direct technical effect of this is that, under the same inspection conditions, its inspection range is larger, thereby significantly improving the inspection speed, making it particularly suitable for the high-efficiency and rapid inspection requirements in semiconductor wafer manufacturing processes.

[0024] 3. The ultraviolet wide-band, large-field-of-view inspection objective described in this invention innovates in terms of system integration and application flexibility. Compared with some complex existing technologies (such as CN120065493A), this invention provides a single, compact inspection objective that achieves excellent optical performance without relying on complex relay systems or imaging tubes. This modular design greatly simplifies the structure of the entire optical system, reduces the number of optical components, effectively reduces the difficulty of design, processing, and assembly, and significantly reduces manufacturing costs. Furthermore, this objective has the ability to flexibly change the system magnification by changing the tube lenses of different focal lengths, allowing it to easily adapt to different inspection accuracies, different field-of-view sizes, and different camera combinations, greatly expanding its application scenarios.

[0025] 4. The ultraviolet wide-band, large-field-of-view inspection objective lens of this invention achieves superior imaging quality through meticulous optical element design. For example, the first biconvex lens described in the claims has positive optical power, the biconcave lens has negative optical power, and the plano-convex lens has positive optical power. These combinations of lenses with different optical powers, working in conjunction with other meniscus lenses and mirrors, can better correct various aberrations such as spherical aberration, astigmatism, and distortion. Especially in the ultraviolet wide-band, this precise aberration control ensures that the objective lens maintains clear and sharp imaging throughout the entire large field of view, ensuring the accuracy and reliability of defect detection and avoiding missed detections or misjudgments caused by defects in the optical system itself.

[0026] 5. The ultraviolet wide-band, large-field-of-view inspection objective described in this invention is a highly innovative and practical solution. It systematically solves several technical bottlenecks in existing technologies, such as the mutual constraints between high resolution and large field of view, and wide band and short wavelength, achieving comprehensive optimization of performance parameters. Compared with existing technologies, the inspection objective provided by this invention not only has a shorter wavelength and wider band, resulting in higher resolution, but its large field of view also greatly improves inspection efficiency.

[0027] This invention features shorter wavelength, wider band, larger numerical aperture, and larger field of view, which can simultaneously meet the high requirements for resolution, detection range, and detection efficiency. Therefore, it is particularly suitable for defect detection and quality control in semiconductor wafer manufacturing, as well as other industrial inspection and scientific research fields that require high-precision, large field of view, and wide-band optical imaging. Attached Figure Description

[0028] Figure 1 This is a structural diagram of a wide-band ultraviolet detection objective lens according to an embodiment of the present invention. The reference numerals are as follows: first lens group G1, second lens group G2, third lens group G3, fourth lens group G4, object plane O, first lens 1, first meniscus lens 2, spherical reflector 3, first biconvex lens 4, biconcave lens 5, first plano-convex lens 6, second meniscus lens 7, second biconvex lens 8, aperture 9, third meniscus lens 10, third biconvex lens 11, fourth meniscus lens 12, fifth meniscus lens 13, fourth biconvex lens 14, mirror surface S11 on the side of the lens closest to the object plane, and reflecting surface S31 of the spherical reflector.

[0029] Figure 2 This is a diagram of the coating area of ​​a UV wide-band large field-of-view detection objective lens according to an embodiment of the present invention. The reference numerals are: first lens annular reflective film A, first lens anti-reflective film B, and first lens annular transition region C.

[0030] Figure 3 This is a modulation transfer function (MTF) curve of an ultraviolet wide-band large field-of-view detection objective lens according to an embodiment of the present invention;

[0031] Figure 4 This is a wavefront aberration map of a wide-band ultraviolet detection objective lens with different fields of view, as described in an embodiment of the present invention.

[0032] Figure 5 This is an axial chromatic aberration curve of an ultraviolet wide-band large field-of-view detection objective lens as described in an embodiment of the present invention;

[0033] Figure 6 This is a structural diagram of a wide-band ultraviolet detection objective lens according to an embodiment of the present invention. The reference numerals are: second lens 31, sixth meniscus lens 101, second plano-convex lens 111, seventh meniscus lens 141, and surface S32 of the second lens on the convex side.

[0034] Figure 7 This is a diagram of the coating area of ​​a UV wide-band large field-of-view detection objective lens according to an embodiment of the present invention. The reference numerals are: second lens annular reflective film D, second lens anti-reflection film E, and second lens annular transition region F.

[0035] Figure 8This is a modulation transfer function (MTF) curve of an ultraviolet wide-band large field-of-view detection objective lens according to an embodiment of the present invention;

[0036] Figure 9 This is a wavefront aberration map of a wide-band ultraviolet detection objective lens with different fields of view, as described in an embodiment of the present invention.

[0037] Figure 10 This is an axial chromatic aberration curve of an ultraviolet wide-band large field-of-view detection objective lens as described in an embodiment of the present invention; Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Implementation Method 1

[0040] like Figure 1 As shown, a wide-band ultraviolet detection objective lens includes a first lens group G1, a second lens group G2, a third lens group G3 and a fourth lens group G4 arranged coaxially from the object plane.

[0041] The second lens group G2 includes a first biconvex lens 4, a biconcave lens 5, and a first plano-convex lens 6;

[0042] The third lens group G3 includes a second meniscus lens 7 and a second biconvex lens 8.

[0043] This optical structure, through the coaxial arrangement and combination of multiple lens groups, achieves large field-of-view imaging in the ultraviolet band, significantly improving aberration control and light flux uniformity. The invention team devoted a great deal of creative effort to the design of the lens group sequence, the selection of lens types, and the optimization of optical parameters, enabling the entire system to achieve high resolution, low distortion, and high imaging efficiency over a wide wavelength range, fully demonstrating its innovative design capabilities for complex optical systems.

[0044] Furthermore, the first mirror group G1 includes a first lens 1, a first meniscus lens 2, and a spherical reflector 3 arranged coaxially from the object plane.

[0045] The fourth lens group G4 includes a third meniscus lens 10, a third biconvex lens 11, a fourth meniscus lens 12, a fifth meniscus lens 13, and a fourth biconvex lens 14, which are arranged coaxially from the third lens group G3.

[0046] By precisely arranging the first and fourth lens groups in a specific coaxial order, this invention achieves high imaging quality with a large field of view in the ultraviolet band, significantly reducing aberrations while ensuring the system's light throughput and resolution. The invention team devoted considerable creative effort to designing the lens group combination order, optimizing the curvature of the meniscus lens, and selecting a suitable biconvex lens configuration. This not only solved the aberration accumulation problem caused by multi-lens coupling but also ensured high signal-to-noise ratio imaging performance over a wide wavelength range.

[0047] Furthermore, the second biconvex lens 8 is a thick lens with an aspect ratio greater than 0.83.

[0048] By employing a thicker lens and optimizing the aspect ratio, the aberration control capability of the lens in the ultraviolet band is significantly improved, while also enhancing the system's heat resistance and mechanical stability. The invention team has devoted creative effort to determining the parameters of the thick lens, selecting materials, and conducting optical simulations. This not only overcomes the problem of thermal lensing effect easily generated by conventional thin lenses under high-power ultraviolet light, but also ensures the long-term stable imaging performance of the system.

[0049] Furthermore, the bending direction of the first meniscus lens 2 is the same as the bending direction of the spherical reflector 3.

[0050] By precisely matching the curvature directions of the meniscus lens and the spherical reflector, the light focusing was optimized and aberrations were further compensated. The invention team made numerous creative attempts in optical path simulation, curvature direction design, and system optimization, which enabled the entire optical system to maintain high resolution and low distortion imaging over a wide field of view.

[0051] Furthermore, the ball-shaped reflector 3 has a central opening, the area of ​​which accounts for 5-25% of the surface area of ​​the ball-shaped reflector 3.

[0052] The central opening design effectively reduces occlusion of the optical system while ensuring a balance between the imaging quality and light flux of the reflector. The invention team put in creative effort in determining the opening ratio, opening position, and optimizing its impact on the system's optical performance. This not only took into account the feasibility of machining but also maintained high efficiency and high precision in the optical design.

[0053] Furthermore, an aperture stop 9 is provided between the third mirror group G3 and the fourth mirror group G4.

[0054] Setting an aperture effectively controls the scattering of the incident beam and the size of the light spot, improving image clarity and the signal-to-noise ratio of the optical system. The invention team put in creative effort to optimize the position, size, and optical shading effect of the aperture, achieving stable imaging results under large field-of-view conditions.

[0055] Furthermore, the first lens 1 has a light-transmitting hole at its center, the light-transmitting hole is coated with an anti-reflective film, and a reflective film is coated outside the area of ​​the anti-reflective film. The width of the transition area between the anti-reflective film and the reflective film is less than 0.1 mm.

[0056] This aperture and film structure optimizes the lens's optical efficiency while reducing stray light and reflection losses. The invention team put in creative effort in aperture design, film processing, and precision control of the transition region, enabling the system to maintain uniform imaging even under high-power ultraviolet light conditions.

[0057] Furthermore, the first lens 1 can be any one of a biconvex lens, a plano-convex lens, or a meniscus lens.

[0058] Offering a variety of lens options improves the adaptability and adjustability of the optical system, while facilitating the optimization of imaging effects according to different application requirements. The invention team has made creative efforts in lens type evaluation, optical simulation, and system compatibility testing, thereby achieving a balance between system flexibility and high performance.

[0059] Implementation Method 2

[0060] like Figure 6 As shown, a wide-band ultraviolet detection objective lens includes a first lens group G1, a second lens group G2, a third lens group G3 and a fourth lens group G4 arranged coaxially from the object plane.

[0061] The second lens group G2 includes a first biconvex lens 4, a biconcave lens 5, and a first plano-convex lens 6;

[0062] The third lens group G3 includes a second meniscus lens 7 and a second biconvex lens 8.

[0063] This optical structure, through the coaxial arrangement and combination of multiple lens groups, achieves large field-of-view imaging in the ultraviolet band, significantly improving aberration control and light flux uniformity. The invention team devoted a great deal of creative effort to the design of the lens group sequence, the selection of lens types, and the optimization of optical parameters, enabling the entire system to achieve high resolution, low distortion, and high imaging efficiency over a wide wavelength range, fully demonstrating its innovative design capabilities for complex optical systems.

[0064] Furthermore, the first lens group G1 includes a first lens 1, a first meniscus lens 2, and a second lens 31 arranged coaxially from the object plane.

[0065] The fourth lens group G4 includes a sixth meniscus lens 101, a second plano-convex lens 111, a fourth meniscus lens 12, a fifth meniscus lens 13, and a seventh meniscus lens 141, which are arranged coaxially from the third lens group G3.

[0066] The innovative design of adding a second lens combined with a multi-meniscus lens effectively improves the system's optical path control capability, achieving a more uniform light spot distribution and a high-quality image field. The invention team conducted systematic experiments and computational verifications in lens type selection, curvature matching, and optical material optimization, demonstrating a deep understanding of wide-band imaging and creative design capabilities, enabling the entire optical system to maintain excellent imaging performance under complex optical path conditions.

[0067] Furthermore, the second biconvex lens 8 is a thick lens with an aspect ratio greater than 0.83.

[0068] By employing a thicker lens and optimizing the aspect ratio, the aberration control capability of the lens in the ultraviolet band is significantly improved, while also enhancing the system's heat resistance and mechanical stability. The invention team has devoted creative effort to determining the parameters of the thick lens, selecting materials, and conducting optical simulations. This not only overcomes the problem of thermal lensing effect easily generated by conventional thin lenses under high-power ultraviolet light, but also ensures the long-term stable imaging performance of the system.

[0069] Furthermore, the second lens 31 has a light-passing hole at its center, the light-passing hole is coated with an anti-reflection film, and a reflective film is coated outside the range of the anti-reflection film. The width of the transition area between the anti-reflection film and the reflective film is less than 0.1 mm.

[0070] The design of the light-passing aperture and the fine film layer significantly improves the light flux utilization and reduces stray light, thereby enhancing the system's imaging contrast and resolution. The invention team has conducted extensive creative explorations in the design of the light-passing aperture size, the selection of film layer materials, and the precise control of the transition region, enabling the optical system to maintain excellent performance in complex wavelength bands.

[0071] Furthermore, the first lens 1 has a light-transmitting hole at its center, the light-transmitting hole is coated with an anti-reflective film, and a reflective film is coated outside the area of ​​the anti-reflective film. The width of the transition area between the anti-reflective film and the reflective film is less than 0.1 mm.

[0072] This aperture and film structure optimizes the lens's optical efficiency while reducing stray light and reflection losses. The invention team put in creative effort in aperture design, film processing, and precision control of the transition region, enabling the system to maintain uniform imaging even under high-power ultraviolet light conditions.

[0073] Furthermore, the first lens 1 can be any one of a biconvex lens, a plano-convex lens, or a meniscus lens.

[0074] Offering a variety of lens options improves the adaptability and adjustability of the optical system, while facilitating the optimization of imaging effects according to different application requirements. The invention team has made creative efforts in lens type evaluation, optical simulation, and system compatibility testing, thereby achieving a balance between system flexibility and high performance.

[0075] Implementation Method 3

[0076] This embodiment combines the technical solutions described in the foregoing embodiments, and, in conjunction with actual application scenarios and the process of using the detection objective lens described in this invention, further verifies and explains the technical effects of this invention through specific examples.

[0077] like Figure 1 The diagram shown is a structural diagram of the detection objective lens in this embodiment, wherein all lenses are spherical lenses. The detection objective lens in this embodiment is suitable for the 255nm-465nm wavelength range, has a numerical aperture of 0.9, and a field of view of [missing information]. Starting from object plane 0, the lenses are sequentially grouped as the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4.

[0078] The first lens group G1 includes a first lens 1, a first meniscus lens 2, and a spherical reflector 3 arranged coaxially from the object plane. In this embodiment, the first lens group G1 has positive optical power and adopts a catadioptric structure, which can reduce the system length and the number of lenses.

[0079] like Figure 2 As shown, an annular reflective film A is deposited on the surface S11 of the first lens 1 near the object surface 0, with a light-passing hole in the middle. The light-passing hole is coated with an anti-reflective film B, and the width of the annular transition area C between the reflective film and the anti-reflective film is strictly controlled to be less than 0.1 mm.

[0080] In the implementation method, the annular reflecting surface of the first lens 1 of the detection objective lens is a plane;

[0081] Preferably, the annular reflecting surface of the first lens 1 can be changed to a convex or concave surface.

[0082] The spherical reflector 3 has a central opening, the size of which is determined by the height of the light rays. In this embodiment, the area of ​​the opening in the spherical reflector 3 is a certain percentage of its surface area. .

[0083] The reflective surface S31 of the ball-shaped reflector 3 is coated with a broadband ultraviolet reflective film, and the back of the ball-shaped reflector 3 is machined into a flat surface, which serves as the mounting reference for the detection objective lens in this embodiment, facilitating the assembly and adjustment of the entire system.

[0084] The second lens group G2 includes a first biconvex lens 4, a biconcave lens 5, and a first plano-convex lens 6. In this embodiment, the second lens group G2 has positive optical power, the lenses are made of two different materials, and a small-interval design is used to correct the chromatic aberration and secondary spectrum of the system.

[0085] The third lens group G3 includes a second meniscus lens 7 and a second biconvex lens 8. In this embodiment, the third lens group G3 has positive optical power, and the second biconvex lens 8 adopts a biconvex thick lens design, which can better converge light, compress the system aperture, and at the same time correct the spherical aberration and part of the field curvature of the system.

[0086] In this embodiment, an aperture stop 9 is added between the third lens group G3 and the fourth lens group G4 in the detection objective lens. This is used to limit the entrance pupil diameter and also to limit the entry of stray light, thus partially eliminating stray light.

[0087] The fourth lens group G4 includes a third meniscus lens 10, a third biconvex lens 11, a fourth meniscus lens 12, a fifth meniscus lens 13, and a fourth biconvex lens 14, arranged coaxially from the third lens group G3. In this embodiment, the third meniscus lens 10 in the fourth lens group G4 has negative optical power, the third biconvex lens 11 has positive optical power, the fourth meniscus lens 12 has negative optical power, the fifth meniscus lens 13 has negative optical power, and the fourth biconvex lens 14 has positive optical power. The fourth biconvex lens 14 is mainly used to converge light rays, compress the system aperture, and can also correct some of the system's spherical aberration. The fourth meniscus lens 12 and the fifth meniscus lens 13 are thick meniscus lenses, installed with their meniscus directions opposite each other, mainly used to correct the system's field curvature. The third meniscus lens 10 and the third biconvex lens 11 are used to control the light aperture and correct system aberrations.

[0088] This system is relatively difficult to assemble and adjust, so a translational adjustable element is reserved in the second lens group G2 for aberration compensation during assembly and adjustment. An interval is reserved between the second lens group G2 and the third lens group G3 for axial compensation during assembly and adjustment.

[0089] In this embodiment, all lenses of the testing objective are designed with a spherical surface, which facilitates processing and testing.

[0090] like Figure 3 As shown, in this embodiment, the modulation transfer function (MTF) of the detection objective lens reaches the diffraction limit.

[0091] like Figure 4 As shown, in this embodiment, the wavefront aberrations of the detection objective lens across the entire field of view are all less than [a certain value]. .

[0092] like Figure 5 As shown, the detection objective lens in this embodiment achieves achromatic aberration.

[0093] Table 1 lists the specific parameters of the detection objective lens in this embodiment, including radius values. A positive value indicates that the center of curvature is closer to the image side, and the radius value... A negative value indicates that the center of curvature is closer to the object side. The units for radius, thickness, and diameter are all millimeters.

[0094] Table 1. Specific parameters of UV broadband large field-of-view testing objectives G2 / G3 / G4 for Implementation Method 1

[0095]

[0096] Table 2. Specific parameters of the UV broadband large field-of-view detection objective lens G1 in Implementation Method 1

[0097]

[0098] The ultraviolet wide-band, large-field-of-view inspection objective shown in this embodiment achieves a high numerical aperture (0.9) and high resolution in the 255nm-465nm wavelength range through a four-lens coaxial arrangement and a catadioptric structure. Excellent imaging performance across the field of view. The system employs a rational combination of positive and negative optical powers in each lens group, combined with thick lenses, meniscus lenses, and the aperture design of the spherical reflector, effectively correcting spherical aberration, field curvature, and chromatic aberration. Simultaneously, the entrance pupil diameter is limited by the aperture stop, reducing stray light and improving the system's signal-to-noise ratio. The anti-reflection coating and annular reflective coating design of the first lens and spherical reflector precisely control the width of the transition region, effectively increasing light throughput and reducing reflection loss. Through reserved lens translation and spacing adjustments, the system can achieve aberration and axial compensation during assembly and adjustment, ensuring the stability of the optical system. The overall design enables the testing objective lens to simultaneously achieve high resolution, low distortion, and apochromatic aberration under wide wavelength and large field of view conditions, achieving excellent imaging results.

[0099] Implementation Method 4

[0100] This embodiment combines the technical solutions described in the foregoing embodiments, and, in conjunction with actual application scenarios and the process of using the detection objective lens described in this invention, further verifies and explains the technical effects of this invention through specific examples.

[0101] This embodiment replaces some lenses with those in embodiment two, as detailed below:

[0102] like Figure 6 The diagram shown is a structural diagram of the detection objective lens in this embodiment, wherein all lenses are spherical lenses. The detection objective lens in this embodiment is suitable for the 255nm-465nm wavelength range, has a numerical aperture of 0.9, and a field of view of [missing information]. Starting from object plane 0, the lenses are arranged in the following order: first lens group G1, second lens group G2, third lens group G3, and fourth lens group G4.

[0103] The first lens group G1 includes a first lens 1, a first meniscus lens 2, and a second lens 31 arranged coaxially from the object plane. In this embodiment, the first lens group G1 has positive optical power and adopts a catadioptric structure, which can reduce the system length and the number of lenses. The first meniscus lens 2 is used to correct the spherical aberration of the system.

[0104] like Figure 7 As shown, an annular reflective film D is deposited on the convex side surface S32 of the second lens 31, with a light-passing hole in the middle. The light-passing hole is coated with an anti-reflective film E, and the width of the annular transition area F between the reflective film and the anti-reflective film is strictly controlled to be less than 0.1 mm.

[0105] The second lens group G2 includes a first biconvex lens 4, a biconcave lens 5, and a first plano-convex lens 6. In this embodiment, the second lens group G2 has positive optical power, the lenses are made of two different materials, and a small-interval design is used to correct the chromatic aberration and secondary spectrum of the system.

[0106] The third lens group G3 includes a second meniscus lens 7 and a second biconvex lens 8. In this embodiment, the third lens group G3 has positive optical power, and the second biconvex lens 8 adopts a biconvex thick lens design, which can better converge light, compress the system aperture, and at the same time correct the spherical aberration and part of the field curvature of the system.

[0107] The fourth lens group G4 includes a sixth meniscus lens 101, a second plano-convex lens 111, a fourth meniscus lens 12, a fifth meniscus lens 13, and a seventh meniscus lens 141, arranged coaxially from the third lens group G3. In this embodiment, the sixth meniscus lens 101 in the fourth lens group G4 has negative optical power, the second plano-convex lens 111 has positive optical power, the fourth meniscus lens 12 has positive optical power, the fifth meniscus lens 13 has negative optical power, and the seventh meniscus lens 141 has negative optical power. The seventh meniscus lens 141 and the fifth meniscus lens 13 have opposite meniscus directions and are mainly used to compress the system aperture, while also correcting some of the system's field curvature and chromatic aberration. The second plano-convex lens 111 and the fourth meniscus lens 12 are used to converge light and correct system spherical aberration. The sixth meniscus lens 101 mainly corrects the system's spherical aberration and distortion.

[0108] In this embodiment, an aperture stop 9 is added between the sixth meniscus lens 101 and the second plano-convex lens 111 in the fourth lens group of the detection objective lens. This is used to limit the entrance pupil diameter and also to limit the entry of stray light, thus partially eliminating stray light.

[0109] This system is relatively difficult to assemble and adjust, so a translational adjustable element is reserved in the second lens group G2 for aberration compensation during assembly and adjustment. The interval between the second lens group G2 and the third lens group G3 is reserved for axial compensation during assembly and adjustment, and the eccentricity of the first meniscus lens 2 is reserved to correct system errors.

[0110] In this embodiment, all lenses of the testing objective are designed with a spherical surface, which facilitates processing and testing.

[0111] like Figure 8 As shown, in this embodiment, the modulation transfer function (MTF) of the detection objective lens reaches the diffraction limit.

[0112] like Figure 9 As shown, in this embodiment, the wavefront aberrations of the detection objective lens across the entire field of view are all less than [a certain value]. .

[0113] like Figure 10 As shown, the detection objective lens in this embodiment achieves achromatic aberration.

[0114] Table 3 lists the specific parameters of the detection objective lens in this embodiment, including radius values. A positive value indicates that the center of curvature is closer to the image side, and the radius value... A negative value indicates that the center of curvature is closer to the object side. The units for radius, thickness, and diameter are all millimeters.

[0115] Table 3. Specific parameters of UV broadband large field-of-view testing objectives G2 / G3 / G4 in Implementation Method 2

[0116]

[0117] Table 4. Specific parameters of the first lens group G1 of the UV wide-band large field-of-view detection objective lens in Implementation Method 2.

[0118]

[0119] The detection objective lens described in this embodiment maintains a wavelength range of 255nm-465nm, a numerical aperture of 0.9, and... Building upon the existing field of view, the overall optical performance was further enhanced through the replacement and optimization of some lenses. The system retains the four-lens coaxial arrangement and catadioptric structure. The first lens group employs a positive optical power design, with the first meniscus lens used to correct spherical aberration. The second lens features a ring-shaped reflective coating and an anti-reflection coating to increase light throughput and reduce reflection loss. The second lens group uses a small-interval combination of two lenses made of different materials to correct chromatic aberration and second-order spectral distortion. The third lens group's thick biconvex lens design better converges light, compresses the system aperture, and corrects spherical aberration and some field curvature. The fourth lens group uses a combination of a six-meniscus lens and a second plano-convex lens. Through a reasonable combination of positive and negative optical powers, comprehensive correction of spherical aberration, field curvature, chromatic aberration, and distortion is achieved. An aperture stop is placed between the sixth meniscus lens and the second plano-convex lens to effectively limit the entrance pupil aperture and suppress stray light. In terms of system assembly and adjustment, aberration and axial compensation are achieved through lens translation, interval adjustment, and the off-center setting of the first meniscus lens, ensuring the stability and adjustment flexibility of the optical system. All lenses in the entire optical system are spherical, facilitating fabrication and testing. Its modulation transfer function reaches the diffraction limit, and its full-field wavefront aberration is less than [value missing]. And achieve the elimination of color difference.

[0120] Based on Embodiment 2, this embodiment replaces the spherical reflector of the first mirror group in Embodiment 2 with the second lens and optimizes the reflective film design. It also adjusts the lens combination and optical power distribution of the fourth mirror group (introducing the seventh meniscus lens and the second plano-convex lens), sets an aperture stop in the fourth mirror group, and adds an eccentric adjustment to the first meniscus lens to improve system error. Thus, while maintaining the wide band and large field of view characteristics, it achieves further optimization of wavefront aberration and apochromatic aberration.

[0121] The above detailed description of the technical solution provided by the present invention is intended to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above detailed embodiments are not intended to limit the scope of protection of the present invention. Any reasonable modifications and improvements to the present invention, recombination of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0122] Those skilled in the art will understand that the above description is merely a preferred embodiment of the present invention, and the features described in the various embodiments and / or claims disclosed in the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle scope of the present invention should be considered to fall within the protection scope of the present invention.

[0123] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A wide-band ultraviolet detection objective lens with a large field of view, characterized in that, The detection objective lens includes a first lens group (G1), a second lens group (G2), a third lens group (G3), and a fourth lens group (G4) arranged coaxially from the object plane. The second lens group (G2) includes a first biconvex lens (4), a biconcave lens (5), and a first plano-convex lens (6); The third lens group (G3) includes a second meniscus lens (7) and a second biconvex lens (8); The first mirror group (G1) includes a first lens (1), a first meniscus lens (2) and a spherical reflector (3) arranged coaxially from the object plane. The fourth lens group (G4) includes a third meniscus lens (10), a third biconvex lens (11), a fourth meniscus lens (12), a fifth meniscus lens (13), and a fourth biconvex lens (14) arranged coaxially from the third lens group (G3). The ball-shaped reflector (3) has a central opening.

2. The testing objective lens according to claim 1, characterized in that, The first lens group (G1) is replaced by a first lens (1), a first meniscus lens (2) and a second lens (31) arranged coaxially from the object plane. The fourth lens group (G4) is replaced by the sixth meniscus lens (101), the second plano-convex lens (111), the fourth meniscus lens (12), the fifth meniscus lens (13) and the seventh meniscus lens (141) arranged coaxially from the third lens group (G3). The second lens (31) has a light-passing hole at its center, and the light-passing hole is coated with an anti-reflection film. A reflective film is coated outside the range of the anti-reflection film.

3. The testing objective lens according to claim 1, characterized in that, The second biconvex lens (8) is a thick lens with a diameter-to-thickness ratio greater than 0.

83.

4. The testing objective lens according to claim 1, characterized in that, The bending direction of the first meniscus lens (2) is the same as that of the spherical reflector (3).

5. The testing objective lens according to claim 1, characterized in that, The ball-shaped reflector (3) has a central opening, the area of ​​which accounts for 5-25% of the surface area of ​​the ball-shaped reflector (3).

6. The testing objective lens according to claim 1, characterized in that, An aperture stop (9) is provided between the third lens group (G3) and the fourth lens group (G4).

7. The testing objective lens according to claim 2, characterized in that, The second lens (31) has a light-passing hole at its center, and the light-passing hole is coated with an anti-reflection film. A reflective film is coated outside the range of the anti-reflection film, and the width of the transition area between the anti-reflection film and the reflective film is less than 0.1 mm.

8. The detection objective lens according to claim 1 or 2, characterized in that, The first lens (1) has a light-passing hole at its center, and the light-passing hole is coated with an anti-reflection film. A reflective film is coated outside the range of the anti-reflection film, and the width of the transition area between the anti-reflection film and the reflective film is less than 0.1 mm.

9. The detection objective lens according to claim 1 or 2, characterized in that, The first lens (1) can be any one of a biconvex lens, a plano-convex lens, or a meniscus lens.

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