A large field of view telecentric optical imaging system for chip overlay systems

Abstract

The application discloses a large-view-field telecentric optical imaging system for a chip overlay system and relates to the technical field of optical imaging systems; the system comprises a diaphragm, a first light-splitting prism, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a second light-splitting prism and an image plane, and the diaphragm, the first light-splitting prism, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the second light-splitting prism and the image plane are sequentially arranged along an optical axis from an object side to an image side. The large-view-field telecentric optical imaging system for the chip overlay system has the advantages of a large field of view, a long object distance, high telecentricity on the object side and low distortion; the incident surface and the emergent surface are loaded with light-splitting prisms matched with multiple functional interfaces, and can simultaneously satisfy functions such as light source illumination, self-focusing and high-resolution imaging.

Description

Technical Field

[0001] This invention relates to the field of optical imaging systems, and in particular to a large field-of-view telecentric optical imaging system for chip overlay systems. Background Technology

[0002] Telecentric optical imaging systems are imaging systems where the angle of incidence of light is close to zero during the imaging process. This reduces astigmatism, avoids image distortion and blurring, and yields clearer and more accurate imaging results. In chip inspection, large-field-of-view telecentric optical imaging systems can provide a wide field of view, allowing the entire chip to be covered in a single imaging session. This reduces the need for multiple movements and adjustments to the imaging system, thereby improving inspection efficiency.

[0003] Chinese Patent Publication No. CN202310337302.7 discloses a high-definition telecentric optical imaging system and its imaging method, belonging to the field of wide-angle imaging system equipment. The high-definition telecentric optical imaging system has a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the incident direction of light from left to right. The first lens is a meniscus lens with negative optical power, the second lens is a plano-concave lens with negative optical power, the third lens is a meniscus lens with positive optical power, the fourth and eighth lenses are both plano-convex lenses with positive optical power, the fifth lens is a biconcave lens with negative optical power, and the sixth and seventh lenses are both biconvex lenses with positive optical power. The fifth and sixth lenses are closely connected to form a cemented assembly. Overall, it has advantages such as low distortion, stable magnification, reduced imaging perspective error, better image resolution, reduced edge position uncertainty, and greater depth of field; however, existing telecentric optical imaging systems for chip inspection have a small field of view, short object distance, low object-side telecentricity, high distortion, and a single functional interface on the incident and exit surfaces. Summary of the Invention

[0004] The purpose of this invention is to provide a large field-of-view telecentric optical imaging system for chip overlay systems, which enables large field-of-view imaging for chip surface inspection, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A large field-of-view telecentric optical imaging system for chip overlay systems includes an aperture, a first beam splitter, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a second beam splitter, and an image plane. The aperture, the first beam splitter, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the second beam splitter, and the image plane are arranged sequentially from the object side to the image side along the optical axis.

[0007] Furthermore, the front end of the first split prism is provided with an entrance pupil, which is located at the object-side focal plane.

[0008] Furthermore, the first beam splitter is made of two right-angled prisms bonded together, used to combine light rays and enhance illumination. The first beam splitter includes a microscope objective interface and a light source interface.

[0009] Furthermore, the second beam splitter is made of two right-angled prisms bonded together. The second beam splitter splits the light into two paths, which are used for self-focusing and imaging, respectively.

[0010] Furthermore, the air gap between the aperture stop and the first beam splitter is between 23 mm and 24 mm; the air gap between the first beam splitter and the first lens is between 100 mm and 160 mm; and the air gap between the first lens and the second lens is between 1.5 mm and...

[0011] The air gap between the second lens and the third lens is between 2.5 mm and 2.5 mm.

[0012] The air gap between the third lens and the fourth lens is between 0.95mm and 1.25mm; the air gap between the fourth lens and the fifth lens is between 0.95mm and 1.25mm; the air gap between the fifth lens and the sixth lens is between 0.95mm and 1.25mm; the air gap between the sixth lens and the second beam splitter is between 83mm and 100mm; and the air gap between the second beam splitter and the image plane is between 35mm and 40mm.

[0013] Furthermore, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses.

[0014] Furthermore, the object-side surface of the first lens is concave, and its image-side surface is convex, giving the first lens negative optical power; the object-side surface of the second lens is convex, and its image-side surface is concave, giving the second lens negative optical power; both the object-side and image-side surfaces of the third lens are convex, giving the third lens positive optical power; the object-side surface of the fourth lens is concave, and its image-side surface is convex, giving the fourth lens negative optical power; the object-side surface of the fifth lens is convex, and its image-side surface is concave, giving the fifth lens positive optical power; and the object-side surface of the sixth lens is convex, and its image-side surface is concave, giving the sixth lens negative optical power.

[0015] Further, the refractive indices of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are n1, n2, n3, n4, n5, and n6, respectively; the Abbe numbers of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are v1, v2, v3, v4, v5, and v6, respectively; wherein, 1.55≤n1≤1.7; 55≤v1≤65; 1.4≤n2≤1.6; 60≤v2≤66; 1.5≤n3≤1.7; 60≤v3≤80; 1.6≤n4≤1.8; 45≤v4≤65; 1.4≤n5≤1.6; 60≤v5≤66; 1.5≤n6≤1.7; and 40≤v6≤50.

[0016] Furthermore, the effective focal length of the first beam splitter, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the second beam splitter is 200mm, the relative numerical aperture is F / 8.0, and a 2 / 3" CCD is used for reception.

[0017] Furthermore, the first beam splitter, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the second beam splitter have a full field of view of 12 degrees and an operating wavelength of 450 nm to 700 nm.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. The first beam splitter, first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and second beam splitter of the present invention have an effective focal length of 200mm and a relative numerical aperture of F / 8.0, which results in a large field of view, high object telecentricity, and the use of a 2 / 3" CCD receiver, which has the advantages of long object distance and low distortion.

[0020] 2. The first beam splitter of the present invention includes a microscope objective interface and a light source interface, and the second beam splitter splits the light into two paths, which are used for self-focusing and imaging respectively. Therefore, the incident surface and the exit surface are equipped with beam splitters that match multiple functional interfaces, which can simultaneously satisfy functions such as light source illumination, self-focusing and high-resolution imaging. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the large field-of-view telecentric optical imaging system of the chip overlay system of the present invention.

[0022] Figure 2 This is a schematic diagram of the interface structure of the large field-of-view telecentric optical imaging system of the present invention;

[0023] Figure 3 This is the MTF curve of the large field-of-view telecentric optical imaging system of the present invention;

[0024] Figure 4 This is a diagram showing the field curvature and distortion data of the large field-of-view telecentric optical imaging system of the present invention.

[0025] In the diagram: 1. Aperture; 2. First beam splitter; 3. First lens; 4. Second lens; 5. Third lens; 6. Fourth lens; 7. Fifth lens; 8. Sixth lens; 9. Second beam splitter; 10. Image plane. Detailed Implementation

[0026] 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 some embodiments of the present invention, and not all embodiments. 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.

[0027] To address the significant limitations and high costs associated with existing technologies in field applications, please refer to [link / reference needed]. Figure 1-4 This embodiment provides the following technical solution:

[0028] A large field-of-view telecentric optical imaging system for chip overlay systems includes an aperture stop 1, a first beam splitter 2, a first lens 3, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, a sixth lens 8, a second beam splitter 9, and an image plane 10. The aperture stop 1, the first beam splitter 2, the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, the sixth lens 8, the second beam splitter 9, and the image plane 10 are arranged sequentially from the object side to the image side along the optical axis.

[0029] Specifically: The front end of the first split prism 2 is set with an entrance pupil position, which is located at the object-side focal plane to ensure that the principal rays incident on the image plane 10 meet the requirements of the image-side telecentric optical path.

[0030] Specifically: The first beam splitter 2 is made of two right-angled prisms glued together, and is used to combine light rays and enhance illumination. The first beam splitter 2 includes a microscope objective interface and a light source interface.

[0031] Specifically: The second beam splitter 9 is made of two right-angled prisms bonded together. The second beam splitter 9 splits the light into two paths, which are used for self-focusing and imaging, respectively.

[0032] The first beam splitter 2 and the second beam splitter 9 can be selected for placement or omission as needed. The first beam splitter 2 is used to combine light rays and enhance illumination, including the microscope objective interface and the light source interface. The first beam splitter 2 can split the incident beam into two beams with a certain light intensity ratio, namely transmitted and reflected beams, thereby realizing the function of the coaxial interface. The second beam splitter 9 is used to split the light rays into two beams for self-focusing and imaging.

[0033] Specifically: the air gap between aperture 1 and the first beam splitter 2 is between 23mm and 24mm; the air gap between the first beam splitter 2 and the first lens 3 is between 100mm and 160mm; the air gap between the first lens 3 and the second lens 4 is between 1.5mm and 2.5mm; the air gap between the second lens 4 and the third lens 5 is between 2.5mm and 3.7mm; the air gap between the third lens 5 and the fourth lens 6 is between 0.95mm and 1.25mm; the air gap between the fourth lens 6 and the fifth lens 7 is between 0.95mm and 1.25mm; the air gap between the fifth lens 7 and the sixth lens 8 is between 0.95mm and 1.25mm; the air gap between the sixth lens 8 and the second beam splitter 9 is between 83mm and 100mm; and the air gap between the second beam splitter 9 and the image plane 10 is between 35mm and 40mm.

[0034] Specifically: Lens 3, 4, 5, 6, 7, and 8 are all spherical lenses. Lens 3 has a concave object-side surface and a convex image-side surface, and has negative optical power. Lens 4 has a convex object-side surface and a concave image-side surface, and has negative optical power. Lens 5 has both a convex object-side surface and a convex image-side surface, and has positive optical power. Lens 6 has a concave object-side surface and a convex image-side surface, and has negative optical power. Lens 7 has a convex object-side surface and a concave image-side surface, and has positive optical power. Lens 8 has a convex object-side surface and a concave image-side surface, and has negative optical power.

[0035] And 3.2 < |f1 / f| < 3.8, 0.85 < |f2 / f| < 1.0, 0.32 < |f3 / f| < 0.38, 0.9 < |f4 / f| < 1.1, 0.56 < |f5 / f| < 0.6, 0.45 < |f6 / f| < 0.49, where f is the focal length of the object-side telecentric optical imaging system, and f1, f2, f3, f4, f5, and f6 are the focal lengths of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8, respectively.

[0036] Specifically: the refractive indices of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 are n1, n2, n3, n4, n5, and n6, respectively; the Abbe numbers of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 are v1, v2, v3, v4, v5, and v6, respectively; where 1.55≤n1≤1.7; 55≤v1≤65; 1.4≤n2≤1.6; 60≤v2≤66; 1.5≤n3≤1.7; 60≤v3≤80; 1.6≤n4≤1.8; 45≤v4≤65; 1.4≤n5≤1.6; 60≤v5≤66; 1.5≤n6≤1.7; and 40≤v6≤50.

[0037] Example 1: The air gap between aperture 1 and the first beam splitter 2 is 23.5 mm; the air gap between the first beam splitter 2 and the first lens 3 is 130 mm; the air gap between the first lens 3 and the second lens 4 is 2.0 mm; the air gap between the second lens 4 and the third lens 5 is 3.1 mm; the air gap between the third lens 5 and the fourth lens 6 is 1.1 mm; the air gap between the fourth lens 6 and the fifth lens 7 is 1.1 mm; the air gap between the fifth lens 7 and the sixth lens 8 is 1.1 mm; the air gap between the sixth lens 8 and the second beam splitter 9 is 91.5 mm; the air gap between the second beam splitter 9 and the image plane 10 is 3 mm. 7.5mm; wherein the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8 are all spherical lenses. The object-side surface of the first lens 3 is concave, and its image-side surface is convex, and the first lens 3 has negative optical power; the object-side surface of the second lens 4 is convex, and its image-side surface is concave, and the second lens 4 has negative optical power; both the object-side surface and the image-side surface of the third lens 5 are convex, and the third lens 5 has positive optical power; the object-side surface of the fourth lens 6 is concave, and its image-side surface is convex, and the fourth lens 6 has negative optical power; the object-side surface of the fifth lens 7 is convex, and its image-side surface is concave, and the fifth lens 7 has positive optical power; the object-side surface of the sixth lens 8 is convex, and its image-side surface is concave, and the sixth lens 8 has negative optical power.

[0038] Let f be the focal length of the object-side telecentric optical imaging system, and let f1, f2, f3, f4, f5, and f6 be the focal lengths of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8, respectively. Then f1 / f = 3.5, f2 / f = 0.925, f3 / f = 0.35, f4 / f = 1.0, f5 / f = 0.58, and f6 / f = 0.47.

[0039] Example 2:

[0040] The air gap between aperture 1 and the first beam splitter 2 is set to 24 mm; the air gap between the first beam splitter 2 and the first lens 3 is set to 155 mm; the air gap between the first lens 3 and the second lens 4 is set to 2.0 mm; the air gap between the second lens 4 and the third lens 5 is set to 3.1 mm; the air gap between the third lens 5 and the fourth lens 6 is set to 1.1 mm; the air gap between the fourth lens 6 and the fifth lens 7 is set to 1.1 mm; the air gap between the fifth lens 7 and the sixth lens 8 is set to 1.1 mm; the air gap between the sixth lens 8 and the second beam splitter 9 is set to 98 mm; and the air gap between the second beam splitter 9 and the image plane 10 is set to 39 mm. Lens 3, 4, 5, 6, 7, and 8 are all spherical lenses. Lens 3 has a concave object-side surface and a convex image-side surface, and has negative optical power. Lens 4 has a convex object-side surface and a concave image-side surface, and has negative optical power. Lens 5 has both a convex object-side surface and a convex image-side surface, and has positive optical power. Lens 6 has a concave object-side surface and a convex image-side surface, and has negative optical power. Lens 7 has a convex object-side surface and a concave image-side surface, and has positive optical power. Lens 8 has a convex object-side surface and a concave image-side surface, and has negative optical power.

[0041] Let f be the focal length of the object-side telecentric optical imaging system, and let f1, f2, f3, f4, f5, and f6 be the focal lengths of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, and the sixth lens 8, respectively. Then f1 / f = 3.75, f2 / f = 0.98, f3 / f = 0.35, f4 / f = 1.0, f5 / f = 0.58, and f6 / f = 0.47.

[0042] Comparing Embodiment 1 and Embodiment 2, it can be seen that, given the inconvenience of air gaps between lenses, as the air gaps between aperture 1 and the first beam splitter 2, between the first beam splitter 2 and the first lens 3, and between the second beam splitter 9 and the image plane 10 increase, the focal length f of the corresponding object-side telecentric optical imaging system also increases.

[0043] Specifically: the effective focal length of the first beam splitter 2, the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, the sixth lens 8, and the second beam splitter 9 is 200mm, the relative numerical aperture is F / 8.0, and a 2 / 3" CCD is used for reception.

[0044] Specifically: the first beam splitter 2, the first lens 3, the second lens 4, the third lens 5, the fourth lens 6, the fifth lens 7, the sixth lens 8, and the second beam splitter 9 have a full field of view of 12 degrees and an operating wavelength of 450 nm to 700 nm.

[0045] Table 1 shows the radius of curvature, center thickness, refractive index, and Abbe number of each lens in the telecentric optical system provided in the embodiment, wherein the units of radius of curvature and center thickness are millimeters (mm).

[0046] Table 1

[0047]

[0048]

[0049] In this context, the radius of curvature is Infinity, representing a plane. The plane with surface number STO is aperture 1, surface number 2 is the object-side surface of the first beam splitter 2, surface number 3 is the image-side surface of the first beam splitter 2, surface number 4 is the object-side surface of the first lens 3, surface number 5 is the image-side surface of the first lens 3, surface number 6 is the object-side surface of the second lens 4, surface number 7 is the image-side surface of the second lens 4, surface number 8 is the object-side surface of the third lens 5, surface number 9 is the image-side surface of the third lens 5, surface number 10 is the object-side surface of the fourth lens 6, and surface number 11 is the fourth… The image-side surface of lens 6, surface number 12 is the object-side surface of the fifth lens 7, surface number 13 is the image-side surface of the fifth lens 7, surface number 15 is the object-side surface of the sixth lens 8, surface number 15 is the image-side surface of the sixth lens 8, surface number 16 is the object-side surface of the second beam splitter 9, surface number 17 is the image-side surface of the second beam splitter 9, and surface number A is image surface 10; d refers to the center thickness of each lens or the distance between adjacent vertices of the lens, n is the refractive index of the material used in each lens, and v is the Abbe number of the material used in each lens.

[0050] like Figure 2 As shown, the first beam splitter 2 of the large field-of-view telecentric optical imaging system is adapted to the microscope objective interface and the light source interface, and the second beam splitter 9 is adapted to the autofocus and imaging equipment.

[0051] like Figure 3 As shown, the MTF value at 140 lp / mm is greater than 0.2 across the entire field of view. This system can be used in conjunction with the infinity correction objective of the chip overlay system to achieve high-resolution imaging.

[0052] like Figure 4 As shown, Figure 4 The left image is the field curvature diagram under the full field of view, with a field curvature of less than 0.1 mm;

[0053] Figure 4The right figure shows the distortion diagram under the full field of view, with distortion less than 0.3%. From the field curvature diagram and the distortion diagram, it can be concluded that the large field of view telecentric optical imaging system used in the chip overlay system has the advantages of high imaging quality and low distortion under a large field of view.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A large field-of-view telecentric optical imaging system for chip overlay systems, comprising an aperture stop (1), a first beam splitter (2), a first lens (3), a second lens (4), a third lens (5), a fourth lens (6), a fifth lens (7), a sixth lens (8), a second beam splitter (9), and an image plane (10), characterized in that: The aperture (1), the first beam splitter (2), the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), the sixth lens (8), the second beam splitter (9), and the image plane (10) are arranged sequentially from the object side to the image side along the optical axis; The first beam splitter (2) is made of two right-angle prisms bonded together, used to combine light rays and enhance illumination. The first beam splitter (2) includes a microscope objective interface and a light source interface. The air gap between the aperture stop (1) and the first beam splitter (2) is between 23 mm and 24 mm; the air gap between the first beam splitter (2) and the first lens (3) is between 100 mm and 160 mm; the air gap between the first lens (3) and the second lens (4) is between 1.5 mm and 2.5 mm; and the air gap between the second lens (4) and the third lens (5) is between 2.5 mm and 3.7 mm. The air gap between the third lens (5) and the fourth lens (6) is between 0.95 mm and 1.25 mm; the air gap between the fourth lens (6) and the fifth lens (7) is between 0.95 mm and 1.25 mm; the air gap between the fifth lens (7) and the sixth lens (8) is between 0.95 mm and 1.25 mm; the air gap between the sixth lens (8) and the second beam splitter (9) is between 83 mm and 100 mm; the air gap between the second beam splitter (9) and the image plane (10) is between 35 mm and 40 mm.

2. The large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 1, characterized in that: The entrance pupil is located at the front end of the first beam splitter (2), and the entrance pupil is located on the object focal plane.

3. The large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 2, characterized in that: The second beam splitter (9) is made of two right-angle prisms glued together. The second beam splitter (9) splits the light into two paths, which are used for self-focusing and imaging, respectively.

4. The large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 3, characterized in that: The first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7) and the sixth lens (8) are all spherical lenses.

5. A large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 4, characterized in that: The object side of the first lens (3) is concave, and its image side is convex, so the first lens (3) has negative optical power; the object side of the second lens (4) is convex, and its image side is concave, so the second lens (4) has negative optical power; the object side and image side of the third lens (5) are both convex, so the third lens (5) has positive optical power; the object side of the fourth lens (6) is concave, and its image side is convex, so the fourth lens (6) has negative optical power; the object side of the fifth lens (7) is convex, and its image side is concave, so the fifth lens (7) has positive optical power; the object side of the sixth lens (8) is convex, and its image side is concave, so the sixth lens (8) has negative optical power.

6. The large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 3, characterized in that: The refractive indices of the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), and the sixth lens (8) are n1, n2, n3, n4, n5, and n6, respectively; the Abbe numbers of the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), and the sixth lens (8) are v1, v2, v3, v4, v5, and v6, respectively; where 1.55≤n1≤1.7; 55≤v1≤65; 1.4≤n2≤1.6; 60≤v2≤66; 1.5≤n3≤1.7; 60≤v3≤80; 1.6≤n4≤1.8; 45≤v4≤65; 1.4≤n5≤1.6; 60≤v5≤66; 1.5≤n6≤1.7; and 40≤v6≤50.

7. A large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 3, characterized in that: The effective focal length of the first beam splitter (2), the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), the sixth lens (8), and the second beam splitter (9) is 200mm, the relative numerical aperture is F / 8.0, and a 2 / 3" CCD is used for reception.

8. A large field-of-view telecentric optical imaging system for chip overlay systems as described in claim 3, characterized in that: The first beam splitter (2), the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), the sixth lens (8), and the second beam splitter (9) have a full field of view of 12deg and a working wavelength of 450nm-700nm.

Images