Broadband-spectrum large-target-surface tube lens and imaging method thereof

Abstract

The invention relates to the field of industrial detection and optical lenses, in particular to a wide-spectrum large-target-surface tube lens in a microscopic imaging system and an imaging method of the wide-spectrum large-target-surface tube lens. An optical system of the tube lens comprises a first double-convex positive lens, a second double-concave negative lens, a third meniscus negative lens, a fourth double-convex positive lens, a fifth double-concave negative lens, a sixth double-convex positive lens, a seventh double-concave negative lens and an eighth double-convex positive lens which are sequentially arranged in the incident direction of light. Wherein the first biconvex positive lens, the second biconcave negative lens and the third meniscus negative lens form a first negative gluing group; and the fourth double-convex positive lens, the fifth double-concave negative lens and the sixth double-convex positive lens form a second positive gluing group. The wide-spectrum large-target-surface tube lens can be matched with a microscope objective for use, and is applied to the field of industrial detection.

Description

Technical Field

[0001] This invention relates to the fields of industrial inspection and optical lenses, and particularly to a broadband large-target-area tube lens and its imaging method in a microscopic imaging system. Background Technology

[0002] In microscopic industrial inspection scenarios such as semiconductor manufacturing and microelectronic component inspection, the spectral coverage, field of view, and imaging accuracy of optical imaging systems directly determine the inspection efficiency and defect identification accuracy.

[0003] With the increasing demands for detection accuracy and efficiency, the microscope objective, a key component of traditional microscopic imaging systems, has significant limitations: it is only compatible with the 400-700nm visible light band, making it difficult to meet the needs of wide-spectrum detection; the target surface of the compatible cameras is mostly less than 1 inch, and the detection of large-size samples requires multiple scans and stitching, which limits efficiency and accuracy; the color difference correction under wide spectrum is insufficient, which can easily affect the recognition and judgment of the detection equipment, thereby interfering with the algorithm; the focal length is mostly between 160 and 200 mm, which limits the overall magnification of the imaging system when used with the microscope objective.

[0004] Industrial testing is currently developing towards the integration of "wide-spectrum multi-dimensional analysis, large field of view rapid detection, and high-precision quantitative measurement." However, traditional tube endoscopes can no longer meet the comprehensive needs, and there is an urgent need to develop high-performance tube endoscopes with wide spectrum and large target surface to break through technical bottlenecks and support the technological upgrading of the field. Summary of the Invention

[0005] The purpose of this invention is to provide a wide-spectrum large-target-area tube mirror and its imaging method. This wide-spectrum large-target-area tube mirror can perform aberration correction in a wide spectral range of 320nm~1100nm, improve system resolution in the ultraviolet band, and be used for deep structure penetration imaging in the near-infrared band. At the same time, it can also take into account conventional visible light detection scenarios and has high imaging quality.

[0006] The technical solution of the present invention is as follows: a broadband large target surface tube lens, the optical system of which includes a first biconvex positive lens, a second biconcave negative lens, a third meniscus negative lens, a fourth biconvex positive lens, a fifth biconcave negative lens, a sixth biconvex positive lens, a seventh biconcave negative lens, and an eighth biconvex positive lens arranged sequentially along the incident direction of light; wherein, the first biconvex positive lens, the second biconcave negative lens, and the third meniscus negative lens form a first negative cemented group; and the fourth biconvex positive lens, the fifth biconcave negative lens, and the sixth biconvex positive lens form a second positive cemented group.

[0007] Furthermore, the optical system satisfies the following relationship: The air gap between the third crescent-shaped negative lens and the fourth biconvex positive lens is 0.2~2mm; The air gap between the sixth biconvex positive lens and the seventh biconcave negative lens is 15mm~30mm; The air gap between the seventh biconcave negative lens and the eighth biconvex positive lens is 15mm~30mm.

[0008] Furthermore, the first biconvex positive lens to the eighth biconvex negative lens are all spherical mirrors.

[0009] Furthermore, the optical system satisfies the following relationship: 1<|fU1 / f|<5; 0.1 < |fU2 / f| < 0.7; 0.1 < |fG7 / f| < 0.7; 0.2 < |fG8 / f| < 0.7; Where f is the focal length of the optical system, fU1 is the focal length of the first negative cemented group, fU2 is the focal length of the second positive cemented group, fG7 is the focal length of the seventh biconcave negative lens, and fG8 is the focal length of the eighth biconvex positive lens.

[0010] Furthermore, the optical system satisfies the following relationship: 0.2 < |L / f| < 0.7; Where L is the distance from the vertex of the front surface of the first biconvex positive lens to the vertex of the rear surface of the eighth biconvex positive lens, and f is the focal length of the optical system.

[0011] Furthermore, the optical system satisfies the following relationship: 0.2 < |BFL / f| < 0.7; Where BFL is the optical back intercept of the optical system, and f is the focal length of the optical system.

[0012] Furthermore, the optical system satisfies the following relationship: 0.1 < |y' / f| < 0.5; Where y' is the half-image height of the optical system and f is the focal length of the optical system.

[0013] Furthermore, the optical system satisfies the following relationship: 1.4 <n1<1.6,35<v1<80; 1.4 <n2<1.6,60<v2<70; 1.4 <n3<1.6,50<v3<70; 1.4 <n4<1.6,60<v4<80; 1.4 <n5<1.6,60<v5<80; 1.4 <n6<1 .6,60<v6<80; 1.5 <n7<1.7,50<v7<70; 1.5 <n8<1.7,50<v8<70; Wherein, n1 to n8 are the refractive indices of the first biconvex positive lens to the eighth biconvex negative lens, respectively, and v1 to v8 are the Abbe coefficients of the first biconvex positive lens to the eighth biconvex negative lens, respectively.

[0014] Furthermore, the optical system satisfies the following relationship: 0.1 < |fG1 / fU1| < 0.3; 0.5 < |fG4 / fU2| < 0.7; Wherein, fG1 is the focal length of the first biconvex positive lens, fG4 is the focal length of the fourth biconvex positive lens, fU1 is the focal length of the first negative cemented group, and fU2 is the focal length of the second positive cemented group.

[0015] An imaging method for a broadband large-target-surface tube lens includes a broadband large-target-surface tube lens, wherein light rays pass sequentially from the object side to the image side along the incident direction through a first biconvex positive lens, a second biconcave negative lens, a third meniscus negative lens, a fourth biconvex positive lens, a fifth biconcave negative lens, a sixth biconvex positive lens, a seventh biconcave negative lens, and an eighth biconvex positive lens before forming an image on the imaging plane.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention adopts a four-group eight-element structure, which achieves apochromatic correction in a wide spectral range. It can be adapted to infinite conjugate microscope objectives, taking into account high-resolution ultraviolet and deep-penetrating infrared imaging. It can also be adapted to large-area cameras to meet various industrial testing needs.

[0017] 2. This invention realizes a wide-spectrum large target surface tube lens optical system with a focal length of 400mm, which can also accommodate infinite conjugate microscope objectives with an entrance pupil diameter of up to 23mm. The working wavelength range is 320~1100nm, with high chromatic aberration correction level and optical distortion of less than 0.1%. It can be adapted to detectors with a maximum target surface of 83mm. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the lens structure of a broadband large target surface tube mirror according to the present invention; Figure 2 This is a system MTF diagram of a broadband large-target-area tube mirror according to the present invention; Figure 3 This is a system field curvature and system distortion aberration diagram of a broadband large-target-area tube mirror according to the present invention; Figure 4 This is a system axial chromatic aberration diagram of a broadband large-target-area tube mirror according to the present invention; Figure 5 This is a system magnification chromatic aberration diagram of a broadband large-target-area tube mirror according to the present invention; Figure 6 This is a system ray aberration curve of a broadband large-target-area tube mirror according to the present invention; In the diagram: G1 - First biconvex positive lens, G2 - Second biconcave negative lens, G3 - Third meniscus negative lens, G4 - Fourth biconvex positive lens, G5 - Fifth biconcave negative lens, G6 - Sixth biconvex positive lens, G7 - Seventh biconcave negative lens, G8 - Eighth biconvex positive lens, U1 - First negative cemented group, U2 - Second positive cemented group. Detailed Implementation

[0019] To make the above features and advantages of the present invention more readily understood, specific embodiments are described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0020] refer to Figures 1 to 6 A broadband large-target-area telescope is characterized in that its optical system comprises, sequentially arranged along the incident direction of light, a first biconvex positive lens G1, a second biconcave negative lens G2, a third meniscus negative lens G3, a fourth biconvex positive lens G4, a fifth biconcave negative lens G5, a sixth biconvex positive lens G6, a seventh biconcave negative lens G7, and an eighth biconvex positive lens G8; wherein the first biconvex positive lens G1, the second biconcave negative lens G2, and the third meniscus negative lens G3 form a first negative cemented group U1; and the fourth biconvex positive lens G4, the fifth biconcave negative lens G5, and the sixth biconvex positive lens G6 form a second positive cemented group U2. This broadband large-target-area telescope has a focal length f of 400 mm, a spectral range of 320 nm to 1100 nm, and a maximum target area of ​​83 mm.

[0021] In this embodiment, the optical system satisfies the following relationship: The air gap between the third crescent-shaped negative lens G3 and the fourth biconvex positive lens G4 is 0.2~2mm; The air gap between the sixth biconvex positive lens G6 and the seventh biconcave negative lens G7 is 15mm~30mm; The air gap between the seventh biconcave negative lens G7 and the eighth biconvex positive lens G8 is 15mm~30mm.

[0022] In this embodiment, the first biconvex positive lens G1 to the eighth biconvex negative lens G8 are all spherical mirrors.

[0023] In this embodiment, the optical system satisfies the following relationship: 1<|fU1 / f|<5; 0.1 < |fU2 / f| < 0.7; 0.1 < |fG7 / f| < 0.7; 0.2 < |fG8 / f| < 0.7; Where f is the focal length of the optical system, fU1 is the focal length of the first negative cemented group U1, fU2 is the focal length of the second positive cemented group U2, fG7 is the focal length of the seventh biconcave negative lens G7, and fG8 is the focal length of the eighth biconvex positive lens G8.

[0024] In this embodiment, the relationship satisfied by the optical system is: 0.2 < |L / f| < 0.7; Where L is the distance from the vertex of the front surface of the first biconvex positive lens G1 to the vertex of the rear surface of the eighth biconvex positive lens G8, and f is the focal length of the optical system.

[0025] In this embodiment, the relationship satisfied by the optical system is: 0.2 < |BFL / f| < 0.7; Where BFL is the back focal length of the optical system, and f is the focal length of the optical system.

[0026] In this embodiment, the relationship satisfied by the optical system is: 0.1 < |y’ / f| < 0.5; Where y’ is the semi-image height of the optical system, and f is the focal length of the optical system.

[0027] In this embodiment, the relationship satisfied by the optical system is: 1.4 < n1 < 1.6, 35 < v1 < 80; [[ID=3�]]1.4 < n2 < 1.6, 60 < v2 < 70; 1.4 < n3 < 1.6, 50 < v3 < 70; 1.4 < n4 < 1.6, 60 < v4 < 80; 1.4 < n5 < 1.6, 60 < v5 < 80; 1.4 < n6 < 1.6, 60 < v6 < 80; 1.5 < n7 < 1.7, 50 < v7 < 70; 1.5 < n8 < 1.7, 50 < v8 < 70; Where n1 to n8 are the refractive indices of the first biconvex positive lens G1 to the eighth biconvex negative lens G8 in sequence, and v1 to v8 are the Abbe numbers of the first biconvex positive lens G1 to the eighth biconvex negative lens G8 in sequence. When v1 < 75, the chromatic aberration correction ability of the system will decline; when 1.5 < n8 < 1.7 is not satisfied, the optical power of the eighth lens will decline, and the spherical aberration and coma will deteriorate.

[0028] In this embodiment, the optical system satisfies the following relationship: 0.1 < |fG1 / fU1| < 0.3; 0.5 < |fG4 / fU2| < 0.7; Wherein, fG1 is the focal length of the first biconvex positive lens G1, fG4 is the focal length of the fourth biconvex positive lens G4, fU1 is the focal length of the first negative cementitious group U1, and fU2 is the focal length of the second positive cementitious group U2. When |fG1 / fU1| < 0.3, and it uses a high-dispersion material, the first negative cementitious group and the second positive cementitious group jointly correct the chromatic aberration of the system, effectively improving the overall optical performance.

[0029] In this embodiment, the lens data of the optical system is as follows: .

[0030] In this embodiment, the broadband large target surface tube mirror satisfies the following parameters: 1. Focal length: f400mm; 2. Entrance pupil diameter: 23mm; 3. Overall optical length: <530mm; 4. Optical back focal length: >195mm; 5. Distortion: <0.1%; 6. Entrance pupil position: 120mm; 7. Applicable wavelength: 320-1100nm; 8. Applicable detector target surface: ≤83mm.

[0031] In this embodiment, Figure 1 The optical structure of the present invention is characterized by a 4-group, 8-piece structure. Figure 2 It demonstrates that the MTF (Mean Transmission Frequency) is close to the diffraction limit across the entire field of view. From Figure 3 As can be seen, the system has a small field curvature, ensuring that the center edge of the image is sharp at the same time, with relative distortion of less than 0.1% and very small deformation. From Figure 4 It can be seen that the system's spherical aberration and axial color difference corrections are good, reaching the level of apochromatic aberration. From Figure 5 It can be seen that the system has good magnification chromatic aberration correction, and the magnification chromatic aberration is much smaller than that of the Airy disk in the 320-1100nm wide spectrum. From Figure 6 It can be seen that the overall aberration of the system is uniform, and the coma is relatively small.

[0032] In this imaging method of a broadband large target lens, light rays pass sequentially from the object side to the image side along the incident direction through a first biconvex positive lens G1, a second biconcave negative lens G2, a third meniscus negative lens G3, a fourth biconvex positive lens G4, a fifth biconcave negative lens G5, a sixth biconvex positive lens G6, a seventh biconcave negative lens G7, and an eighth biconvex positive lens G8 before forming an image on the imaging surface.

[0033] The above description is only a preferred embodiment of the present invention. For those skilled in the art, designing different forms of a broadband large target surface tube mirror according to the guidance of the present invention does not require creative labor. All equivalent changes, modifications, substitutions and variations made in accordance with the scope of the patent application of the present invention without departing from the principles and spirit of the present invention shall be covered by the present invention.

Claims

1. A broadband large-target-area tube mirror, characterized in that, The optical system of the tube lens includes a first biconvex positive lens (G1), a second biconcave negative lens (G2), a third meniscus negative lens (G3), a fourth biconvex positive lens (G4), a fifth biconcave negative lens (G5), a sixth biconvex positive lens (G6), a seventh biconcave negative lens (G7), and an eighth biconvex positive lens (G8) arranged sequentially along the incident direction of light. Among them, the first biconvex positive lens (G1), the second biconcave negative lens (G2), and the third meniscus negative lens (G3) form a first negative cemented group (U1); the fourth biconvex positive lens (G4), the fifth biconcave negative lens (G5), and the sixth biconvex positive lens (G6) form a second positive cemented group (U2).

2. The broadband large-target-area tube mirror according to claim 1, characterized in that, The optical system satisfies the following relationship: The air gap between the third crescent-shaped negative lens (G3) and the fourth biconvex positive lens (G4) is 0.2~2mm; The air gap between the sixth biconvex positive lens (G6) and the seventh biconcave negative lens (G7) is 15mm~30mm; The air gap between the seventh biconcave negative lens (G7) and the eighth biconvex positive lens (G8) is 15mm~30mm.

3. A broadband large-target-area tube mirror according to claim 1 or 2, characterized in that, The first biconvex positive lens (G1) to the eighth biconvex negative lens (G8) are all spherical mirrors.

4. A broadband large-target-area tube mirror according to claim 1, characterized in that, The optical system satisfies the following relationship: 1<|fU1 / f|<5; 0.1 < |fU2 / f| < 0.7; 0.1 < |fG7 / f| < 0.7; 0.2 < |fG8 / f| < 0.7; Where f is the focal length of the optical system, fU1 is the focal length of the first negative cemented group (U1), fU2 is the focal length of the second positive cemented group (U2), fG7 is the focal length of the seventh biconcave negative lens (G7), and fG8 is the focal length of the eighth biconvex positive lens (G8).

5. A broadband large-target-area tube mirror according to claim 1, 2, or 4, characterized in that, The optical system satisfies the following relationship: 0.2 < |L / f| < 0.7; Where L is the distance from the vertex of the front surface of the first biconvex positive lens (G1) to the vertex of the rear surface of the eighth biconvex positive lens (G8), and f is the focal length of the optical system.

6. A broadband large-target-area tube mirror according to claim 1, 2, or 4, characterized in that, The optical system satisfies the following relationship: 0.2 < |BFL / f| < 0.7; Where BFL is the optical back intercept of the optical system, and f is the focal length of the optical system.

7. A broadband large-target-area tube mirror according to claim 1, 2, or 4, characterized in that, The optical system satisfies the following relationship: 0.1 < |y' / f| < 0.5; Where y' is the half-image height of the optical system and f is the focal length of the optical system.

8. A broadband large-target-area tube mirror according to claim 1, 2 or 4, characterized in that, The optical system satisfies the following relationship: 1.4 <n1<1.6,35<v1<80; 1.4 <n2<1.6,60<v2<70; 1.4 <n3<1.6,50<v3<70; 1.4 <n4<1.6,60<v4<80; 1.4 <n5<1.6,60<v5<80; 1.4 <n6<1 .6,60<v6<80; 1.5 <n7<1.7,50<v7<70; 1.5 <n8<1.7,50<v8<70; Wherein, n1 to n8 are the refractive indices of the first biconvex positive lens (G1) to the eighth biconvex negative lens (G8) respectively, and v1 to v8 are the Abbe coefficients of the first biconvex positive lens (G1) to the eighth biconvex negative lens (G8) respectively.

9. A broadband large-target-area tube mirror according to claim 1, 2 or 4, characterized in that, The optical system satisfies the following relationship: 0.1 < |fG1 / fU1| < 0.3; 0.5 < |fG4 / fU2| < 0.7; Wherein, fG1 is the focal length of the first biconvex positive lens (G1), fG4 is the focal length of the fourth biconvex positive lens (G4), fU1 is the focal length of the first negative cementitious group (U1), and fU2 is the focal length of the second positive cementitious group (U2).

10. An imaging method for a broadband large-target-area tube mirror, comprising the broadband large-target-area tube mirror as described in any one of claims 1-9, characterized in that, The light rays pass sequentially from the object side to the image side along the incident direction through the first biconvex positive lens (G1), the second biconcave negative lens (G2), the third meniscus negative lens (G3), the fourth biconvex positive lens (G4), the fifth biconcave negative lens (G5), the sixth biconvex positive lens (G6), the seventh biconcave negative lens (G7), and the eighth biconvex positive lens (G8) before forming an image on the imaging plane.

Images