A microscope objective lens and microscopic optical system, and a detection device

Abstract

A microscope objective, a microscopic optical system, and a detection device are disclosed. The objective includes a meniscus lens, a spherical aberration lens group, a chromatic aberration lens group, a distortion lens group, and an aberration lens group, arranged coaxially from the object side to the image side. The meniscus lens collects the light beam emitted from the object side into the objective and shapes the beam; the spherical aberration lens group eliminates spherical aberration generated by the meniscus lens; the chromatic aberration lens group eliminates at least the chromatic aberration generated by the meniscus lens and the spherical aberration lens group; the distortion lens group eliminates at least the distortion generated by the meniscus lens, the spherical aberration lens group, and the chromatic aberration lens group; and the aberration lens group adjusts at least the basic parameters of the microscope objective to correct aberrations. Based on this, a microscope objective with a large numerical aperture based on a wide optical spectrum such as 400-1200 nm can be realized, thereby improving the measurement accuracy of overlay measurement equipment.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to a microscope objective and a microscopic optical system and detection device. Background Technology

[0002] Overlay measurement equipment is crucial for ensuring the yield of integrated circuits. The principle of overlay measurement involves using an optical microscopic imaging system to obtain the overlay target pattern of two layers. The alignment between the two layers directly affects the overall device performance and yield. Then, based on digital image algorithms, the center position of each layer is calculated to obtain the overlay error. The microscope objective is the most critical component, directly affecting the detection resolution and speed. The resolution of the microscope objective is related to its operating wavelength and numerical aperture (NA); the higher the NA, the higher the resolution. The detection speed is typically related to the light source intensity and instrument sensitivity. Current solutions to reduce measurement errors include shortening the operating wavelength of the microscope objective to visible light, such as 400nm-700nm. However, when the spectrum is too wide, resolution decreases, distortion increases, and chromatic aberration becomes significant. Moreover, the light source spectrum and microscope performance cannot be simultaneously matched, which has a significant impact on measurement accuracy. Therefore, current technologies generally use 400nm-700nm microscope objectives, but detection accuracy and chromatic aberration need further improvement.

[0003] Furthermore, the advanced process requirements of 300nm wafers / 20-14nm process nodes necessitate measurement accuracy of 0.5nm in overlay metrology equipment. Conventional microscope objectives, however, cannot achieve high-resolution, high-precision raw image acquisition in bright-field optical microscopy or high numerical aperture, high angular resolution scattering imaging. They also fail to meet the requirements in terms of the wide spectral range of 400nm-1200nm and optical aberration parameters such as distortion and chromatic aberration. Therefore, a high numerical aperture, high angular resolution microscope objective based on a wide spectral range of 400nm-1200nm is needed to improve the resolution and accuracy of detection. Summary of the Invention

[0004] In view of the above problems, the present invention provides a microscope objective and a microscopic optical system and a detection device, which are described in detail below.

[0005] According to the first aspect, one embodiment provides a microscope objective lens, comprising: a meniscus lens, a spherical aberration lens group, a chromatic aberration lens group, a distortion lens group, and an aberration lens group arranged coaxially from the object side to the image side.

[0006] The meniscus lens is used to collect the light beam emitted from the objective side into the microscope objective and to shape the light beam.

[0007] The spherical aberration lens group is used to eliminate the spherical aberration generated by the meniscus lens. The spherical aberration lens group includes an eleventh lens group and a tenth lens group arranged coaxially from the object side to the image side.

[0008] The chromatic aberration lens group is used to at least eliminate the chromatic aberration generated by the meniscus lens and the spherical aberration lens group. The chromatic aberration lens group includes a ninth lens group and an eighth lens group arranged coaxially from the object side to the image side.

[0009] The distortion lens group is used at least to eliminate the distortions produced by the meniscus lens, the spherical aberration lens group, and the chromatic aberration lens group. The distortion lens group includes a seventh lens group and a sixth lens group arranged coaxially from the object side to the image side.

[0010] The aberration lens group is used at least to adjust the basic parameters of the microscope objective to correct aberrations. The aberration lens group includes a fifth lens group, a fourth lens, a third lens, a second lens, and a first lens arranged coaxially from the object side to the image side.

[0011] According to a second aspect, one embodiment provides a microscopic optical system, comprising: an objective lens portion and a tube lens portion arranged coaxially in sequence; the objective lens portion is a microscope objective lens as described above; the tube lens portion is used to focus and image the light beam collimated by the objective lens portion.

[0012] According to a third aspect, one embodiment provides a detection device, comprising:

[0013] A light source is used to provide an illumination beam to the object being inspected.

[0014] An illumination lens assembly is used to adjust the size, direction, and uniformity of the illumination beam emitted by the light source;

[0015] The microscope objective lens described above is used to magnify the features in the object to be detected;

[0016] The tube lens section is used to image the features of the object under test after magnification by the microscope objective lens; and

[0017] A camera is used to capture features of the object to be detected in the image formed by the telescope.

[0018] According to the microscope objectives, microscopic optical systems, and detection devices described in the above embodiments, the microscope objectives consist of multiple lens groups and a meniscus lens. The meniscus lens can shape the beam at a large aperture angle, and the resulting spherical aberration is eliminated by the spherical aberration lens group. After passing through the chromatic aberration lens group, the chromatic aberration of light of different wavelengths is canceled out. At the same time, the distortion of a large numerical aperture angle is corrected by the distortion lens group, and the aberrations are compensated by the aberration lens group. Thus, a microscope objective with a large numerical aperture based on a wide spectral light band such as 400-1200nm can be realized, thereby improving the measurement accuracy of the overlay measurement equipment.

[0019] According to the microscope objectives, microscopic optical systems, and detection devices described in the above embodiments, a portion of the lens group and meniscus of the microscope objective has positive optical power, while the remaining portion has negative optical power. This allows the focal lengths of the front and rear lenses to compensate for each other. Furthermore, by employing a combination of cemented doublet and cemented triplet lenses, chromatic aberration and distortion are repeatedly eliminated through multiple cementing processes, thereby achieving the requirements of high numerical aperture and high resolution. Moreover, the combination of multiple lenses with both positive and negative optical power can minimize field curvature. Additionally, these lenses can be made of different materials and have different refractive indices, allowing the use of different wavelengths of light for compensation, thereby offsetting aberrations or reducing chromatic aberration. This achieves the elimination and reduction of chromatic aberration and distortion, ultimately improving the measurement accuracy and angular resolution of the overlay measurement equipment.

[0020] The microscope objectives, microscopic optical systems, and detection devices according to the above embodiments have specific limitations on each lens in the microscope objectives, such as the radius of curvature of each surface of each lens and the inter-surface distance. This can effectively solve the problem of apochromatic microscopic imaging in a wide spectral range of 400-1200 nm, with a numerical aperture of 0.9, distortion of only 0.03%, resolution of 0.5 μm, and chromatic aberration of less than 200 nm.

[0021] According to the microscope objectives, microscopic optical systems, and detection devices of the above embodiments, the microscope objectives are provided with an aperture stop, which makes the telecentricity of the entire objective very high, so that the incident angle of the principal ray to the image plane can be as small as possible, for example, less than 0.05°, thereby making the imaging distortion of the microscope objectives less than 0.03% when used for, for example, the detection of semiconductor wafers. Attached Figure Description

[0022] Figure 1 (a) and (b) are schematic diagrams of the composition structure of a microscope objective provided according to some embodiments of the present invention, wherein (b) also shows the optical path diagram inside the objective;

[0023] Figure 2 This is a schematic diagram of a dot array of a microscope objective lens according to some embodiments of the present invention;

[0024] Figure 3 This is a schematic diagram of field curvature distortion of a microscope objective lens according to some embodiments of the present invention;

[0025] Figure 4 This is a schematic diagram of axial chromatic aberration of a microscope objective lens provided according to some embodiments of the present invention;

[0026] Figure 5 This is a schematic diagram of the transverse chromatic aberration of a microscope objective lens provided according to some embodiments of the present invention;

[0027] Figure 6 This is a schematic diagram of the chromatic focus shift of a microscope objective lens according to some embodiments of the present invention;

[0028] Figure 7 This is a schematic diagram of the modulation transfer function curve of a microscope objective lens provided according to some embodiments of the present invention. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0030] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0031] The serial numbers assigned to components in this document, such as "first," "second," etc., are merely for distinguishing the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). Furthermore, the orientations indicated by "front," "rear," "left," "right," etc., used in the following description are based on the orientations or positional relationships shown in the accompanying drawings. These approximations are for ease of description and simplification of the invention and do not indicate or imply that the device, system, or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0032] As mentioned earlier, overlay measurement equipment is used to measure the planar distances between circuit patterns formed in different steps and to detect their differences. It is one of the important pieces of equipment in the semiconductor integrated circuit process chain. Currently, the most commonly used overlay error measurement system is the optical imaging system. Its basic principle is to obtain a digital image of the target pattern using optical microscopy imaging technology, and then use digital image processing algorithms to determine the boundary position of each layer of the target pattern. After determining the center position, the planar distance between the centers of the nth and (n+1)th layers of the pattern structure on the silicon wafer can be calculated, i.e., the overlay error. Since overlay measurement involves a series of errors, such as pattern displacement caused by the measurement system, pattern displacement caused by the wafer under test, and total measurement uncertainty, reducing measurement errors to improve measurement accuracy has become one of the key indicators. In optical microscopy imaging inspection, the microscope objective is the most critical component, directly affecting the detection resolution and detection speed. As mentioned earlier, the higher the numerical aperture of the microscope objective, the higher the detection resolution; however, in the current technology, no high numerical aperture, high angular resolution microscope objective based on 400-1200 nm has been found. One objective of this invention is to provide a microscope objective, a microscopic optical system, and a detection system to address the imaging technology of large numerical aperture (NA > 0.9) apochromatic imaging objectives. Simultaneously, based on project requirements, the design is optimized for conventional microscope objectives, achieving an NA of 0.9, with distortion controlled to 0.03% within the effective area corresponding to the mark size, and a resolution as high as 0.5 μm. Therefore, this invention provides a large numerical aperture microscope objective based on a broad spectral wavelength range of 400-1200 nm, improving the measurement accuracy of overlay measurement equipment.

[0033] Some embodiments of the present invention provide a microscope objective, such as... Figure 1As shown, it includes: a meniscus lens 25, a spherical aberration lens group A, a chromatic aberration lens group B, a distortion lens group C, and an aberration lens group D, arranged coaxially from the object side to the image side. The spherical aberration lens group A includes an eleventh lens group G1 and a tenth lens group G2, arranged coaxially from the object side to the image side, used to eliminate spherical aberration caused by the meniscus lens 25. The chromatic aberration lens group B includes a ninth lens group G3 and an eighth lens group G4, arranged coaxially from the object side to the image side, used to at least eliminate chromatic aberration caused by the meniscus lens 25 and the spherical aberration lens group A. The distortion lens group C includes a seventh lens group G5 and a sixth lens group G6, arranged coaxially from the object side to the image side, used to at least eliminate distortion caused by the meniscus lens 25, the spherical aberration lens group A, and the chromatic aberration lens group B. The aberration lens group D includes a fifth lens group G7, a fourth lens 4, a third lens 3, a second lens 2, and a first lens 1 arranged coaxially from the object side to the image side, and is used at least to adjust the basic parameters of the microscope objective (including but not limited to focal length) to correct aberrations.

[0034] In some embodiments, the meniscus lens 25, the eleventh lens group G1, the tenth lens group G2, the ninth lens group G3, the sixth lens group G6, the fourth lens 4, and the third lens 3 all have positive optical power, while the eighth lens group G4, the seventh lens group G5, the fifth lens group G7, the second lens 2, and the first lens 1 all have negative optical power. In this respect, by placing the positive optical power lens group closer to the object side, light from the object to be detected can be collected and converged towards the image side. Conversely, by placing the negative optical power lens group closer to the image side, light can be diverged, reducing the focal length of the entire system. This allows the objective lens to form a clear image at a shorter distance. Furthermore, through a carefully designed combination of positive and negative lenses, aberrations such as spherical aberration and chromatic aberration can be corrected, thereby improving image quality. Additionally, specific imaging effects can be achieved. Combined with the lens material, size, and other parameters in some embodiments of the present invention, the desired effects of the present invention can be achieved. In some embodiments, the focal length range of each lens group can be [-177.5mm, 114.5mm]. In some embodiments, the microscope objective meets the following conditions: numerical aperture greater than or equal to 0.9, focal length of 1.8 mm, working wavelength between 40 nm and 1200 nm, and working distance greater than 0.15 mm. In some embodiments, by designing the key optical parameters of each lens group (see below for details), the microscope objective can achieve the following effects: resolution greater than or equal to 0.5 μm, imaging distortion less than or equal to 0.03%, and chromatic aberration less than or equal to 200 nm. It should be noted that, with... Figure 1 For example, the object is located in the direction the viewer faces. Figure 1 The far right (i.e.) Figure 1 The image is located to the right of the twenty-fifth lens 25 (the exact location is not shown in the figure), with the image side facing the viewer. Figure 1 The far left (i.e.) Figure 1The left side of the first lens 1 shown in the figure (the specific location is not shown).

[0035] In some embodiments, the meniscus lens 25 and lenses 1 to 24 in each lens group are made of optical glass, and include at least two different types of optical glass. For example, barium crown glass H-BAK7, H-BAK5, heavy crown glass H-ZK10, H-ZK5, a specific type of phosphor crown glass D-ZPK7, D-ZPK1A, D-ZPK7-25, a variant of heavy crown glass H-ZK3A, a specific type of lanthanide optical glass H-ZLAF4LA, D-ZLAF85LN, D-LAF050-25, H-ZLAF68B, D-ZLAF81, D-ZLAF52LA, a specific type of heavy crown glass D-ZK3-25, heavy flint glass H-ZF11, etc.

[0036] The following is a detailed description. Figure 1 The various parts of the microscope objective shown.

[0037] The meniscus lens 25 is used to collect the light beam emitted from the object side into the microscope objective and to shape the beam. In some embodiments, the meniscus lens 25 can magnify the object to be inspected to the target aperture range. Therefore, the meniscus lens 25 can handle beams with large aperture angles. In some embodiments, the meniscus lens 25 may have a thirty-sixth surface S36 near the image side and a thirty-seventh surface S37 near the object side. In a specific example, the radius of curvature of the thirty-sixth surface S36 is 0.70 mm, the radius of curvature of the thirty-seventh surface S37 is 0.55 mm, and the distance between the thirty-seventh surface S37 and the object plane S38 is 0.15 mm. In a specific example, the meniscus lens 25 is made of H-ZLAF68B optical glass.

[0038] In some embodiments, an aperture stop (not shown) may be provided between the meniscus lens 25 and the spherical aberration lens group A to make the telecentricity of the entire microscope objective very high, that is, to make the incident angle of the principal ray to the image plane less than 0.05°, so that the imaging distortion of the microscope objective is less than 0.03% when inspecting semiconductor wafers.

[0039] For the spherical aberration lens group A, the beam emitted from the object side is shaped by the large aperture angle of the approximately hemispherical lens 25. The resulting spherical aberration is first eliminated by the eleventh lens group G1, and then secondly eliminated by the tenth lens group G2. In some embodiments, the eleventh lens group G1 includes a twenty-fourth lens 24, a twenty-third lens 23, and a twenty-second lens 22 arranged coaxially from the object side to the image side. These three lenses 22, 23, and 24 are cemented together to form a cemented triplet lens, which has a thirty-second surface S32 near the tenth lens group G2, a thirty-third surface S33 formed by cementing the twenty-second lens 22 and the twenty-third lens 23, a thirty-fourth surface S34 formed by cementing the twenty-third lens 23 and the twenty-fourth lens 24, and a third surface S34 near the meniscus lens 25. The fifteenth surface S35; the tenth lens group G2 includes a twenty-first lens 21, a twenty-second lens 20, and a nineteenth lens 19 arranged coaxially from the object side to the image side. These three lenses 19, 20, and 21 are cemented together to form a cemented triplet lens, which has a twenty-eighth surface S28 near the chromatic aberration lens group B, a twenty-ninth surface S29 formed by cementing the nineteenth lens 19 and the twenty-second lens 20, a thirtieth surface formed by cementing the twenty-second lens 20 and the twenty-first lens 21, and a thirty-first surface S31 near the eleventh lens group G1. In a specific example, the nineteenth lens 19 is made of H-ZK20, the twenty-second lens 20 is made of H-ZK14, the twenty-first lens 21 is made of H-ZK10L, the twenty-second lens 22 is made of D-ZPK5, the twenty-third lens 23 is made of D-ZK79, and the twenty-fourth lens 24 is made of H-ZBAF1. In a specific example, the radius of curvature of the thirty-fifth surface S35 is -23.05 mm, the radius of curvature of the thirty-fourth surface S34 is -6.84 mm, the radius of curvature of the thirty-third surface S33 is -4.94 mm, the radius of curvature of the thirty-second surface S32 is 3.83 mm, the radius of curvature of the thirty-first surface S31 is -17.43 mm, the radius of curvature of the thirtieth surface S30 is -49.30 mm, the radius of curvature of the twenty-ninth surface S29 is 12.27 mm, and the radius of curvature of the twenty-eighth surface S28 is 38.20 mm.In a specific example, the distance between the twenty-eighth surface S28 and the twenty-ninth surface S29 is 1.00 mm, the distance between the twenty-ninth surface S29 and the thirtieth surface S30 is 1.77 mm, the distance between the thirtieth surface S30 and the thirty-first surface S31 is 1.00 mm, the distance between the thirty-first surface S31 and the thirty-second surface S32 is 0.10 mm, the distance between the thirty-second surface S32 and the thirty-third surface S33 is 2.64 mm, the distance between the thirty-third surface S33 and the thirty-fourth surface S34 is 1.11 mm, the distance between the thirty-fourth surface S34 and the thirty-fifth surface S35 is 0.82 mm, and the distance between the thirty-fifth surface S35 and the thirty-sixth surface S36 of the meniscus lens (25) is 0.02 mm.

[0040] For chromatic aberration lens group B, chromatic aberrations of different wavelengths are canceled out when passing through the ninth lens group G3. The residual chromatic aberration is significantly eliminated after passing through the eighth lens group G4, resulting in an axial chromatic aberration of <200nm. In some embodiments, the ninth lens group G3 includes an eighteenth lens 18, a seventeenth lens 17, and a sixteenth lens 16 arranged coaxially from the object side to the image side. These three lenses 16, 17, and 18 are cemented together to form a cemented triplet lens, which has a twenty-fourth surface S24 near the eighth lens group G4, a twenty-fifth surface S25 formed by cementing the sixteenth lens 16 and the seventeenth lens 17 together, a twenty-sixth surface S26 formed by cementing the seventeenth lens 17 and the eighteenth lens 18 together, and a second surface S26 near the tenth lens group G2. The seventeenth surface S27; the eighth lens group G4 includes a fifteenth lens 15, a fourteenth lens 14, and a thirteenth lens 13 arranged coaxially from the object side to the image side. These three lenses 13, 14, and 15 are cemented together. It has a twentieth surface S20 near the side of the distortion lens group C, a twenty-first surface S21 formed by cementing the thirteenth lens 13 and the fourteenth lens 14, a twenty-second surface S22 formed by cementing the fourteenth lens 14 and the fifteenth lens 15, and a twenty-third surface S23 near the side of the ninth lens group G3. In a specific example, the thirteenth lens 13 is made of D-ZLAF81, the fourteenth lens 14 is made of D-ZPK1A, the fifteenth lens 15 is made of H-ZK5, the sixteenth lens 16 is made of D-ZPK1A, the seventeenth lens 17 is made of D-ZLAF52LA, and the eighteenth lens 18 is made of D-ZPK7-25. In a specific example, the radius of curvature of the twentieth surface S20 is -39.78 mm, the radius of curvature of the twenty-first surface S21 is 7.68 mm, the radius of curvature of the twenty-second surface S22 is -11.97 mm, the radius of curvature of the twenty-third surface S23 is -26.21 mm, the radius of curvature of the twenty-fourth surface is 8.03 mm, the radius of curvature of the twenty-fifth surface is -10.62 mm, the radius of curvature of the twenty-sixth surface is 5.41 mm, and the radius of curvature of the twenty-seventh surface is -10.96 mm.In a specific example, the distance between the twentieth surface S20 and the twenty-first surface S21 is 1.00 mm, the distance between the twenty-first surface S21 and the twenty-second surface S22 is 2.86 mm, the distance between the twenty-second surface S22 and the twenty-third surface S23 is 1.00 mm, the distance between the twenty-third surface S23 and the twenty-fourth surface S24 is 0.10 mm, the distance between the twenty-fourth surface S24 and the twenty-fifth surface S25 is 3.73 mm, the distance between the twenty-fifth surface S25 and the twenty-sixth surface S26 is 1.38 mm, the distance between the twenty-sixth surface S26 and the twenty-seventh surface S27 is 3.61 mm, and the distance between the twenty-seventh surface S27 and the twenty-eighth surface S28 of the tenth lens group G2 is 0.10 mm.

[0041] As mentioned earlier, special cemented triplet lenses G1, G2, and G3 are used throughout the optical path. These lenses have different materials and refractive indices, which can compensate for light of different wavelengths, thereby canceling aberrations or reducing chromatic aberration. That is, in some embodiments of the present invention, the materials and radii of curvature of these lenses are carefully designed so that they can mutually compensate for chromatic aberration and distortion in the synthesized optical system, achieving the elimination and reduction of chromatic aberration and distortion, thereby improving the measurement accuracy and angular resolution of the overlay measurement equipment.

[0042] For the distortion lens group C, the distortion at a larger numerical aperture angle can be corrected by the seventh lens group G5 and the sixth lens group G6. In some embodiments, the seventh lens group G5 includes a twelfth lens 12, an eleventh lens 11, and a tenth lens 10 arranged coaxially from the object side to the image side. These three lenses are cemented together to form a cemented triplet lens. The lens has a sixteenth surface S16 near the sixth lens group G6, a seventeenth surface S17 formed by cementing the tenth lens 10 and the eleventh lens 11 together, an eighteenth surface S18 formed by cementing the eleventh lens 11 and the twelfth lens 12 together, and a nineteenth surface S19 near the eighth lens group G4. The sixth lens group G6 includes a ninth lens 9, an eighth lens 8, and a seventh lens 7 arranged coaxially from the object side to the image side. These three lenses are cemented together to form a cemented triplet lens. The lens has a twelfth surface S12 near the fifth lens group G7, a thirteenth surface S13 formed by cementing the seventh lens 7 and the eighth lens 8 together, a fourteenth surface S14 formed by cementing the eighth lens 8 and the ninth lens 9 together, and a fifteenth surface S15 near the seventh lens group G5. In a specific example, the seventh lens 7 is made of H-BAK5, the eighth lens 8 is made of D-ZLAF85LN, the ninth lens 9 is made of D-ZK3-25, the tenth lens 10 is made of D-LAF050-25, the eleventh lens 11 is made of H-ZF11, and the twelfth lens 12 is made of H-ZLAF68B. In a specific example, the radius of curvature of the twelfth surface S12 is 17.50 mm, the radius of curvature of the thirteenth surface S13 is 56.53 mm, the radius of curvature of the fourteenth surface S14 is 5.47 mm, the radius of curvature of the fifteenth surface S15 is -16.54 mm, the radius of curvature of the sixteenth surface S16 is -15.81 mm, the radius of curvature of the seventeenth surface S17 is 4.43 mm, the radius of curvature of the eighteenth surface S18 is 46.54 mm, and the radius of curvature of the nineteenth surface S19 is -19.15 mm. In a specific example, the distance between the twelfth surface S12 and the thirteenth surface S13 is 1.25 mm, the distance between the thirteenth surface S13 and the fourteenth surface S14 is 1.00 mm, the distance between the fourteenth surface S14 and the fifteenth surface S15 is 2.51 mm, the distance between the fifteenth surface S15 and the sixteenth surface is 2.49 mm, the distance between the sixteenth surface S16 and the seventeenth surface S17 is 1.01 mm, the distance between the seventeenth surface S17 and the eighteenth surface S18 is 2.65 mm, the distance between the eighteenth surface S18 and the nineteenth surface S19 is 1.58 mm, and the distance between the nineteenth surface and the twentieth surface S20 of the eighth lens group G4 is 0.10 mm.

[0043] As mentioned above, this invention utilizes the special design of six sets of cemented triplet lenses G1, G2, G3, G4, G5, and G6, and takes advantage of the excellent achromatic and distortion correction properties of these cemented triplet lenses. This allows the chromatic aberration and distortion inside the objective lens to be repeatedly eliminated through multiple sets of cemented triplet lenses, thereby achieving the requirement of high numerical aperture and high resolution.

[0044] For the aberration lens group D, it includes four groups of single lenses and one group of cemented doublet lenses, namely the fifth lens group G7. The fifth lens group G7 includes a sixth lens 6 and a fifth lens 5 arranged coaxially from the object side to the image side, and the two lenses are cemented together to form a cemented doublet lens. In some embodiments, the first lens 1 has a first surface S1 near the image side and a second surface S2 near the object side; the second lens 2 has a third surface S3 near the image side and a fourth surface S4 near the object side; the third lens 3 has a fifth surface S5 near the image side and a sixth surface S6 near the object side; the fourth lens 4 has a seventh surface S7 near the image side and an eighth surface S8 near the object side; the fifth lens group G7 has a ninth surface S9 near the image side, a tenth surface S10 formed by cementing the fifth lens 5 and the sixth lens 6, and an eleventh surface S11 near the object side. In a specific example, the first lens 1 is made of H-BAK7, the second lens 2 is made of H-ZK10, the third lens 3 is made of D-ZPK7, the fourth lens 4 is made of H-ZK3A, the fifth lens 5 is made of H-ZLAF4LA, and the sixth lens 6 is made of H-BAK7. In a specific example, the radius of curvature of the first surface S1 is -6.04 mm, the radius of curvature of the second surface S2 is -30.41 mm, the radius of curvature of the third surface S3 is -23.40 mm, the radius of curvature of the fourth surface S4 is 10.28 mm, the radius of curvature of the fifth surface S5 is 85.82 mm, the radius of curvature of the sixth surface S6 is -5.90 mm, the radius of curvature of the seventh surface S7 is infinity, the radius of curvature of the eighth surface S8 is -28.34 mm, the radius of curvature of the ninth surface S9 is 744.50 mm, the radius of curvature of the tenth surface S10 is -16.61 mm, and the radius of curvature of the eleventh surface S11 is 8.42 mm. In a specific example, the distance between the first surface S1 and the second surface S2 is 3.29 mm, the distance between the second surface S2 and the third surface S3 is 0.13 mm, the distance between the third surface S3 and the fourth surface S4 is 1.03 mm, the distance between the fourth surface S4 and the fifth surface S5 is 0.46 mm, the distance between the fifth surface S5 and the sixth surface S6 is 4.00 mm, the distance between the sixth surface S6 and the seventh surface S7 is 0.10 mm, the distance between the seventh surface S7 and the eighth surface S8 is 1.01 mm, the distance between the eighth surface S8 and the ninth surface S9 is 0.03 mm, the distance between the ninth surface S9 and the tenth surface S10 is 1.40 mm, the distance between the tenth surface S10 and the eleventh surface S11 is 4.62 mm, and the distance between the eleventh surface S11 and the eleventh surface S11 of the sixth lens group G6 is 13.21 mm.

[0045] As mentioned above, the objective lens of this invention consists of positive and negative optical power lens groups and a meniscus lens. Through the combination of cemented doublet and cemented triplet lenses, the focal length of the front lens and the optical power of the rear lens compensate for each other. The positive chromatic aberration generated by the front lens (the lens closer to the object plane) and the negative chromatic aberration generated by the rear lens (the lens closer to the image plane) cancel each other out in the optical path, and the lens aberrations are compensated for each other. This can effectively achieve apochromatic microscopy imaging with a wide spectral range of 400-1200nm, a numerical aperture of 0.9, distortion of only 0.03%, resolution of 0.5μm, and chromatic aberration below 200nm.

[0046] The working principle of the microscope objective described above will be described below with reference to a preferred embodiment, and the microscope objective proposed in this invention will be further elaborated accordingly. Those skilled in the art will understand that this embodiment is merely a non-limiting implementation of the present invention, intended to clearly demonstrate the main concept of the invention and provide specific methods convenient for public implementation, rather than limiting all functions, operating modes, or optical parameters that the microscope objective can employ. In this embodiment, the microscope objective has a magnification of 100 and an NA of 0.9. The key optical parameters of each lens are shown in Table 1.

[0047]

[0048]

[0049] Table 1

[0050] Please refer to Table 1 and... Figure 1 (See the diagram from left to right, i.e., from the image side to the object side). In Table 1, surface 1 is the first lens 1 closest to the image side (e.g., ...). Figure 1 The first surface is shown in Table 1, surface 2 is the second surface of the first lens 1, and so on; the thickness shown in Table 1 is the distance between the current surface and the next surface, for example, 3.29 mm represents the distance between the first surface of the first lens near the image side and the second surface near the object side (also near the second lens); the material refers to the material of the lens, for example, the material of the first lens 1 is optical glass H-BAK7. The materials exemplified in Table 1 can be optical glass produced, for example, by Chengdu Guangming Optoelectronics Co., Ltd. in China.

[0051] Due to aberrations, the image of a single "point" in object space becomes a speckle of confusion. Obviously, the smaller the speckle, the more concentrated the energy, and the closer it is to the ideal "point-to-point imaging." The point pattern obtained by simulating the microscope objective lens of this embodiment using ZEMAX optical design software is shown below. Figure 2 As shown. By Figure 2As can be seen, the blur spots of the three fields of view (i.e., image plane 0.000mm, image plane 0.005mm, and image plane 0.010mm) of the microscope objective provided in this embodiment are all less than 2μm, and the imaging effect is very good.

[0052] Field curvature (i.e., image field bending) causes distortion, which in turn affects the detection results of the object being examined. Distortion is a type of principal ray aberration, reflecting the similarity between the object and the image; if it is less than 1%, the object and image are considered to be almost perfectly similar. Figure 3 As shown, the inventors used ZEMAX optical design software to simulate the imaging of the microscope objective lens of this embodiment. The left figure is a field curvature diagram. In the figure, the horizontal axis represents the field curvature (unit μm), and the vertical axis represents the field of view (unit angle). The maximum field of view is 0.316 degrees, the sagittal field curvature is 0.0000 mm, and the meridional field curvature is 0.0001 mm. The field curvature of the experimentally formed image is less than 0.5 μm. Obviously, this value meets the requirements of a clear full field of view and achieves the requirements of a flat objective lens. That is, the microscope objective lens of this embodiment has a very good field flat effect. Figure 3 The right figure is a distortion diagram, which shows the corresponding distortion test results. The vertical axis represents the field of view, and the horizontal axis represents the distortion (percentage). The maximum field of view is 0.316 degrees, and the maximum distortion is 0.0201%. The distortion of the experimentally formed image is less than 0.03%, which shows that the imaging distortion of the microscope objective in this embodiment is very small.

[0053] Figure 4 The axial chromatic aberration of the microscope objective lens in this embodiment is schematically illustrated. The vertical axis represents the normalized pupil coordinates, and the horizontal axis represents the longitudinal aberration (unit: mm). The axial chromatic aberration in the aforementioned three fields of view is less than 400 nm, reaching the apochromatic level, meaning that the microscope objective lens in this embodiment has a very good apochromatic effect.

[0054] Figure 5 The diagram schematically illustrates the transverse chromatic aberration of the microscope objective lens in this embodiment. The vertical axis represents the field of view, and the horizontal axis represents lateral aberration (unit: μm). The transverse chromatic aberration in all three fields of view is less than the Airy disk, indicating that the microscope objective lens in this embodiment has excellent achromatic effect.

[0055] Color shift refers to the change in the focusing position of different colors of light within the lens system when the focus of a microscope is adjusted, due to the different refractive indices of these colors. Figure 6 The chromatic focus shift of the microscope objective of this embodiment is schematically shown. The vertical axis of the figure represents the wavelength range and the horizontal axis represents the focus shift, with the unit being μm. It can be seen from the figure that the axial chromatic aberration at 0 field of view is less than 200nm, which means that the microscope objective of this embodiment has a very good achromatic effect.

[0056] The MTF (Modulation Transfer Function) of an objective lens describes the degree of contrast attenuation after an optical system (specifically the objective lens) images sinusoidal wave intensity distribution functions of different frequencies. It is an important indicator of image quality, directly related to image resolution and contrast. The inventors also used ZEMAX optical design software to simulate the MTF curve of the microscope objective lens in this embodiment, and the results showed that the lens resolution reached 2000 lp / mm. Figure 7 As shown.

[0057] Therefore, the microscope objectives, microscopic optical systems, and detection devices provided in some embodiments of the present invention are composed of a positive optical power lens group, a negative optical power lens group, and a meniscus lens. By combining multiple cemented triplet lens groups, positive and negative optical power and chromatic aberration compensation are performed, and lens aberrations are mutually compensated. This effectively achieves apochromatic microscopic imaging with a wide spectral range of 400–1200 nm, a numerical aperture of 0.9, distortion of only 0.03%, resolution of 0.5 μm, and chromatic aberration below 200 nm.

[0058] Based on the microscope objectives provided in some embodiments of the present invention, the present invention also provides a microscopic optical system, which includes an objective lens portion and a tube lens portion arranged coaxially in sequence; the objective lens portion can be the microscope objective lens provided by the present invention described above; the tube lens portion can be used to focus and image the beam collimated by the objective lens portion, and can be implemented using corresponding existing equipment, which will not be described in detail here. Because the microscopic optical system uses the microscope objective lens provided by the present invention, it can at least achieve the effects achievable by the microscope objective lens provided by the present invention, such as achieving apochromatic microscopic imaging with a wide spectral range of 400-1200 nm, a numerical aperture of 0.9, distortion of only 0.03%, resolution of 0.5 μm, and chromatic aberration below 200 nm.

[0059] Based on the microscope objectives provided in some embodiments of the present invention, the present invention also provides a detection device, which includes a light source, an illumination lens group, a microscope objective, a tube lens section, and a camera. The light source provides an illumination beam to the object to be detected; the illumination lens group adjusts the size, direction, and uniformity of the illumination beam emitted by the light source; the microscope objective magnifies features in the object to be detected; the tube lens section images the features in the object to be detected magnified by the microscope objective; and the camera captures the features in the object to be detected imaged by the tube lens section. The light source, illumination lens group, tube lens section, and camera in this detection device can all be implemented using existing equipment, and will not be described in detail here; while the microscope objective can be implemented using the microscope objective provided by the present invention, and will not be described further. Because the detection device uses the microscope objective provided by the present invention, it can at least achieve the effects achievable by the microscope objective provided by the present invention, such as achieving apochromatic microscopy imaging with a wide spectral range of 400–1200 nm, a numerical aperture of 0.9, distortion of only 0.03%, resolution of 0.5 μm, and chromatic aberration below 200 nm.

[0060] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0061] In the above embodiments, implementation can be achieved, in whole or in part, by software, hardware, firmware, or any combination thereof. Furthermore, as those skilled in the art will understand, the principles herein can be reflected in a computer program product on a computer-readable storage medium pre-loaded with computer-readable program code. Any tangible, non-transitory computer-readable storage medium may be used, including magnetic storage devices (hard disks, floppy disks, etc.), optical storage devices (CD-ROMs, DVDs, Blu-ray discs, etc.), flash memory, and / or the like. These computer program instructions can be loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to form a machine, such that instructions executing on the computer or other programmable data processing apparatus can generate means for performing a specified function. These computer program instructions can also be stored in a computer-readable storage medium that can instruct a computer or other programmable data processing apparatus to operate in a particular manner, such that instructions stored in the computer-readable storage medium can form an article of manufacture including means for implementing the specified function. Computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to perform a series of operational steps on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions executed on the computer or other programmable apparatus provide steps for performing a specified function.

[0062] While the principles herein have been illustrated in various embodiments, numerous modifications to the structure, arrangement, proportions, elements, materials, and components, particularly suited to specific environmental and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other alterations or alterations will be included within the scope of this document.

[0063] The foregoing specific descriptions have been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of this disclosure. Therefore, considerations for this disclosure are to be illustrative rather than restrictive, and all such modifications are to be included within its scope. Similarly, advantages, other advantages, and solutions to problems with respect to various embodiments have been described above. However, benefits, advantages, solutions to problems, and any elements that produce these, or make them more explicit, should not be construed as critical, essential, or necessary. The term “comprising” and any other variations thereof as used herein are non-exclusive inclusion, meaning that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed or not part of the process, method, system, article, or apparatus. Furthermore, the term “coupled” and any other variations thereof as used herein refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections, and / or any other connections.

[0064] Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the basic principles of the invention. Therefore, the scope of the invention should be determined only by the claims.

Claims

1. A microscope objective lens, characterized in that, It consists of a meniscus lens (25), a spherical aberration lens group (A), a chromatic aberration lens group (B), a distortion lens group (C), and an aberration lens group (D) arranged coaxially from the object side to the image side; The meniscus lens (25) is used to collect the light beam emitted from the objective side into the microscope objective and to shape the light beam; The spherical aberration lens group (A) is used to eliminate the spherical aberration generated by the meniscus lens (25). The spherical aberration lens group (A) consists of an eleventh lens group (G1) and a tenth lens group (G2) arranged coaxially from the object side to the image side. The chromatic aberration lens group (B) is used at least to eliminate the chromatic aberration generated by the meniscus lens (25) and the spherical aberration lens group (A). The chromatic aberration lens group (B) consists of a ninth lens group (G3) and an eighth lens group (G4) arranged coaxially from the object side to the image side. The distortion lens group (C) is used at least to eliminate the distortions produced by the meniscus lens (25), the spherical aberration lens group (A) and the chromatic aberration lens group (B). The distortion lens group (C) is composed of a seventh lens group (G5) and a sixth lens group (G6) arranged coaxially from the object side to the image side. The aberration lens group (D) is used at least to adjust the basic parameters of the microscope objective to correct aberrations. The aberration lens group (D) consists of a fifth lens group (G7), a fourth lens (4), a third lens (3), a second lens (2), and a first lens (1) arranged coaxially from the object side to the image side. The meniscus lens (25), the eleventh lens group (G1), the tenth lens group (G2), the ninth lens group (G3), the sixth lens group (G6), the fourth lens (4), and the third lens (3) all have positive optical power; The eighth lens group (G4), the seventh lens group (G5), the fifth lens group (G7), the second lens (2), and the first lens (1) all have negative optical power; And / or, the meniscus lens and the lenses in each lens group are all made of optical glass, and contain at least two different types of optical glass. The eleventh lens group (G1) consists of the twenty-fourth lens (24), the twenty-third lens (23), and the twenty-second lens (22) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The tenth lens group (G2) consists of the twenty-first lens (21), the twentieth lens (20) and the nineteenth lens (19) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The ninth lens group (G3) consists of the eighteenth lens (18), the seventeenth lens (17) and the sixteenth lens (16) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The eighth lens group (G4) consists of the fifteenth lens (15), the fourteenth lens (14) and the thirteenth lens (13) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The seventh lens group (G5) consists of the twelfth lens (12), the eleventh lens (11) and the tenth lens (10) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The sixth lens group (G6) consists of a ninth lens (9), an eighth lens (8) and a seventh lens (7) arranged coaxially from the object side to the image side, and the three lenses are cemented together. The fifth lens group (G7) consists of a sixth lens (6) and a fifth lens (5) arranged coaxially from the object side to the image side, and the two lenses are cemented together.

2. The microscope objective lens as described in claim 1, characterized in that, The focal length range of each lens group is [-177.5mm, 114.5mm].

3. The microscope objective lens as described in claim 1, characterized in that, The microscope objective has multiple optical parameters, and each optical parameter satisfies the following: The numerical aperture is greater than or equal to 0.9, the focal length is 1.8 mm, the working band is between 40 nm and 1200 nm, and the working distance is greater than 0.15 mm. Resolution greater than or equal to 0.5μm, imaging distortion less than or equal to 0.03%, and color difference less than or equal to 200nm.

4. The microscope objective lens as described in claim 1, characterized in that, It also includes an aperture disposed between the meniscus lens (25) and the eleventh lens group (G1) to improve the telecentricity of the microscope objective.

5. The microscope objective as described in claim 4, characterized in that, The aperture is used to increase the telecentricity of the microscope objective so that the incident angle of the principal ray to the image plane is less than 0.05°, thereby making the imaging distortion less than or equal to 0.03%.

6. A microscopic optical system, characterized in that, include: An objective lens portion and a tube lens portion are arranged coaxially in sequence; the objective lens portion is a microscope objective lens as described in any one of claims 1-5; the tube lens portion is used to focus and image the light beam after optical magnification by the objective lens portion.

7. A detection device, characterized in that, include: A light source is used to provide an illumination beam to the object being inspected. An illumination lens assembly is used to adjust the size, direction, and uniformity of the illumination beam emitted by the light source; The microscope objective lens as described in any one of claims 1-5 is used to optically magnify features in the object to be detected; The tube lens section is used to image the features of the object under test after optical magnification by the microscope objective lens; and A camera is used to capture features of the object to be detected in the image formed by the telescope.

Images