Coaxial illumination system and optical detection device compatible with large na large aperture optical fibers

Abstract

The application discloses a coaxial illumination system compatible with large-NA large-diameter optical fiber and an optical detection device, and relates to the technical field of coaxial illumination. The coaxial illumination system compatible with large-NA large-diameter optical fiber comprises a first mirror group and a mirror group. The technical scheme of the application is characterized in that the light passing radius of the first mirror group, the light passing radius of the mirror group and the light passing radius of the second mirror group are all positively correlated with the numerical aperture of the optical fiber. When a large-NA large-diameter optical fiber light source is used, the first mirror group, the mirror group and the second mirror group can be expanded to ensure that the light is uniformly distributed while being efficiently transmitted, and the compatibility of the large-NA large-diameter optical fiber light source and the system is realized, the light efficiency is ensured, the uniformity of the illumination of the illumination surface is ensured through the cooperation between the light path adjustment of the mirror group and the second mirror group, the situation that the edge of the illumination surface is dark is avoided, and the illumination effect is improved.

Description

Technical Field

[0001] This invention relates to the field of coaxial lighting technology, and in particular to a coaxial lighting system and optical inspection device compatible with large-aperture optical fibers with large apertures (NA). Background Technology

[0002] Currently, short-wave infrared automatic optical inspection equipment has been widely used in fields such as semiconductor wafer defect inspection and wafer bonding inspection. With its high penetration and high resolution, it achieves non-contact non-destructive testing, improving production efficiency and yield. The microscope head and coaxial light source are the core components of the automatic optical inspection equipment. Only with high uniformity of illumination can the image obtained by the lens be clearer and brighter, ensuring the smooth progress of back-end image processing.

[0003] Most existing coaxial illumination uses 0.22NA fiber optic light sources. When using large NA (Numerical Aperture) fiber optic light sources, there is a problem of low luminous efficacy, which may result in insufficient illumination of the object surface and thus an inability to form a clear image. Summary of the Invention

[0004] The main objective of this invention is to propose a coaxial illumination system and optical inspection device compatible with large-aperture optical fibers with large aperture (NA), aiming to improve the illumination effect while adapting to large-aperture optical fiber light sources.

[0005] To achieve the above objectives, the present invention proposes a coaxial illumination system compatible with large-aperture optical fibers with large NA, comprising:

[0006] The first lens group has a light source on one side;

[0007] A reflector assembly, wherein the first mirror assembly faces the incident mirror surface of the reflector assembly, and an illumination surface is provided on the exit mirror surface side of the reflector assembly, and a second mirror assembly is provided between the incident mirror surface and the exit mirror surface;

[0008] The light transmission radius of the first mirror group, the light transmission radius of the reflector group, and the light transmission radius of the second mirror group are all positively correlated with the numerical aperture of the optical fiber. The first mirror group includes a first cemented lens and a first meniscus lens. After the light source enters the first cemented lens, it passes through the first meniscus lens and the incident mirror surface before entering the reflector group. A variable aperture is provided between the first meniscus lens and the reflector group.

[0009] In one embodiment, the first meniscus lens has a positive optical power, the curvature of the side of the first meniscus lens facing the variable aperture is greater than the curvature of the side of the first meniscus lens away from the variable aperture, and the convex surface of the first meniscus lens faces the variable aperture.

[0010] In one embodiment, the first cemented lens includes a second meniscus lens and a third meniscus lens, wherein the convex surface of the second meniscus lens is cemented to the concave surface of the third meniscus lens, and the convex surface of the third meniscus lens faces the first meniscus lens, and the concave surface of the second meniscus lens faces the light source.

[0011] In one embodiment, the second meniscus lens has a positive optical power, the third meniscus lens has a negative optical power, and the curvature of the third meniscus lens toward the first meniscus lens is greater than the curvature of the second meniscus lens toward the light source.

[0012] In one embodiment, the light transmission radius of the first meniscus lens is larger than that of the third meniscus lens, and the light transmission radius of the first meniscus lens is larger than that of the second meniscus lens.

[0013] In one embodiment, the mirror group includes a mirror and a semi-transparent mirror, the mirror and the semi-transparent mirror being arranged in parallel, and the second mirror group being arranged on the optical path between the mirror and the semi-transparent mirror;

[0014] Wherein, the light transmission radius of the second mirror group is smaller than that of the reflector, and the light transmission radius of the second mirror group is smaller than that of the semi-transparent and semi-reflective mirror.

[0015] In one embodiment, the second lens group includes a fourth meniscus lens and a biconvex lens, wherein the concave surface of the fourth meniscus lens with a large curvature is cemented to the convex surface of the biconvex lens, and the convex surface of the fourth meniscus lens with a small curvature receives the light reflected by the mirror.

[0016] In one embodiment, the fourth meniscus lens has a positive optical power, and the biconvex lens has a negative optical power.

[0017] In one embodiment, an objective lens is provided in the reflected light path of the semi-transparent mirror to project light onto the illumination surface.

[0018] The present invention also proposes an optical detection device, including a coaxial illumination system compatible with large-aperture optical fibers with large NA.

[0019] The technical solution of this invention ensures that the light transmission radii of the first mirror group, the reflector group, and the second mirror group are all positively correlated with the numerical aperture of the optical fiber. When using a large-NA, large-aperture optical fiber light source, the light transmission radii of the first mirror group, the reflector group, and the second mirror group can be expanded to ensure that the light is evenly distributed while transmitting efficiently. This achieves compatibility between the large-NA, large-aperture optical fiber light source and the system, ensuring light efficiency. The coordination between the optical path adjustment of the reflector group and the second mirror group ensures the uniformity of illumination on the illuminated surface, avoiding dim edges of the illuminated surface and improving the illumination effect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 A schematic diagram of an embodiment of the coaxial illumination system compatible with large-aperture optical fibers with large NA provided by the present invention;

[0022] Figure 2 This is a parameter diagram of an embodiment of the coaxial illumination system compatible with large-aperture optical fibers with large NA provided by the present invention.

[0023] Explanation of icon numbers:

[0024] 10. First lens group; 11. Second meniscus lens; 12. Third meniscus lens; 13. First meniscus lens; 30. Variable aperture; 40. Reflecting mirror group; 41. Semi-transparent mirror; 42. Reflecting mirror; 50. Second lens group; 51. Biconvex lens; 52. Fourth meniscus lens; 60. Objective lens; 70. Illumination surface.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0028] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] Currently, short-wave infrared automated optical inspection (AOI) equipment has been widely used in fields such as semiconductor wafer defect detection and wafer bonding inspection. With its high penetration and high resolution, it enables non-contact non-destructive testing, improving production efficiency and yield. The microscope head and coaxial light source are the core components of automated optical inspection equipment. Only with high uniformity of illumination can the image obtained by the lens be clearer and brighter, ensuring the smooth progress of back-end image processing.

[0030] Most existing coaxial illumination uses 0.22NA fiber optic light sources. When using large-NA, large-aperture fiber optic light sources, there is a problem of low luminous efficacy, which may result in insufficient illumination of the object surface, thus making it impossible to form a clear image.

[0031] This invention proposes a coaxial illumination system compatible with large-aperture optical fibers with large NA.

[0032] Please see Figure 1 In one embodiment of the present invention, the coaxial illumination system compatible with large-aperture optical fibers with large NA includes:

[0033] First mirror group 10, with a light source on one side of the first mirror group 10;

[0034] A reflector group 40, wherein the first mirror group 10 faces the incident mirror surface of the reflector group 40, and an illumination surface is provided on the exit mirror surface side of the reflector group 40, and a second mirror group 50 is provided between the incident mirror surface and the exit mirror surface.

[0035] The light transmission radius of the first mirror group 10, the light transmission radius of the reflector group 40, and the light transmission radius of the second mirror group 50 are all positively correlated with the numerical aperture of the optical fiber. The first mirror group 10 includes a first cemented mirror and a first meniscus lens 13. After the light source enters the first cemented mirror, it passes through the first meniscus lens 13 and the incident mirror surface before entering the reflector group 40. A variable aperture 30 is provided between the first meniscus lens 13 and the reflector group 40.

[0036] It is understood that the light emitted by the light source, after being reflected by the first cemented mirror, the first meniscus lens 13 and the variable aperture 30, is projected onto the illumination surface by the reflector group 40, and the exit mirror surface of the reflector group 40 coincides with the imaging optical axis.

[0037] The technical solution of this invention ensures that the light transmission radius of the first mirror group 10, the light transmission radius of the reflector group 40, and the light transmission radius of the second mirror group 50 are all positively correlated with the numerical aperture of the optical fiber. When using a large NA large-aperture optical fiber light source, the first mirror group 10, the reflector group 40, and the second mirror group 50, with their expanded light transmission radii, can ensure that light is transmitted efficiently while achieving uniform distribution. This achieves compatibility of the large NA large-aperture optical fiber light source with the system, ensuring light efficiency. The coordination between the optical path adjustment of the reflector group 40 and the second mirror group 50 ensures the uniformity of illumination on the illumination surface, avoiding dim edges and improving the illumination effect.

[0038] In one embodiment, the first meniscus lens 13 has a positive optical power, the curvature of the side of the first meniscus lens 13 facing the variable aperture 30 is greater than the curvature of the side of the first meniscus lens 13 away from the variable aperture 30, and the convex surface of the first meniscus lens 13 faces the variable aperture 30.

[0039] like Figure 2 As shown, the radius of curvature of the side of the first meniscus lens 13 facing the first cemented lens is greater than the radius of curvature of the side of the first meniscus lens 13 facing the variable aperture 30. In this way, the light propagation path is effectively controlled through the asymmetrical curvature design, so that the light passing through the first meniscus lens 13 can be projected onto the variable aperture 30.

[0040] It is understandable that as the first meniscus lens 13 moves from the side facing the first cemented mirror to the side facing away from the first cemented mirror, its light transmission radius increases. By gradually increasing the beam aperture, it ensures compatibility with large NA light rays, avoids light loss due to aperture mismatch, and indirectly improves the utilization rate of light energy.

[0041] Meanwhile, the variable aperture 30 is disposed on the imaging side of the first meniscus lens 13, and the first meniscus lens 13 is disposed adjacent to the variable aperture 30 to ensure the uniformity of light at the variable aperture 30, so as to provide a uniform light source for the subsequent Köhler illumination system (i.e. the reflector group 40 and the second mirror group 50).

[0042] In one embodiment, the first cemented lens includes a second meniscus lens 11 and a third meniscus lens 12, wherein the convex surface of the second meniscus lens 11 is cemented to the concave surface of the third meniscus lens 12, and the convex surface of the third meniscus lens 12 faces the first meniscus lens 13, and the concave surface of the second meniscus lens 11 faces the light source.

[0043] In one embodiment, the second meniscus lens 11 has a positive optical power, the third meniscus lens 12 has a negative optical power, and the curvature of the side of the third meniscus lens 12 facing the first meniscus lens 13 is greater than the curvature of the side of the second meniscus lens 11 facing the light source.

[0044] like Figure 2 As shown, the radius of curvature of the side of the third meniscus lens 12 facing the first meniscus lens 13 is -10.55mm, while the radius of curvature of the side of the second meniscus lens 11 facing the light source is -16.30mm. The radius of curvature of the cemented surface of the second meniscus lens 11 and the third meniscus lens 12 is -7.82mm, so that the first cemented lens can quickly converge the diverging light emitted by the large-NA large-aperture optical fiber and avoid light scattering due to excessive NA.

[0045] Meanwhile, the light transmission radius of the second meniscus lens 11 facing the light source gradually increases from the light transmission radius of the third meniscus lens 12 facing the first meniscus lens 13, ensuring efficient entry of the beam from the large-NA, large-diameter optical fiber, reducing edge light loss, and laying the foundation for subsequent uniform illumination.

[0046] In one embodiment, the light transmission radius of the first meniscus lens 13 is larger than that of the third meniscus lens 12, and the light transmission radius of the first meniscus lens 13 is larger than that of the second meniscus lens 11.

[0047] It is understandable that the diverging light emitted by the light source passes through the second meniscus lens 11, the third meniscus lens 12 and the first meniscus lens 13 in sequence, and the light transmission radius of the second meniscus lens 11, the third meniscus lens 12 and the first meniscus lens 13 gradually increases, thereby ensuring the efficient entry of the large NA large aperture fiber light source beam and reducing edge loss.

[0048] In one embodiment, the mirror group 40 includes a mirror 42 and a semi-transparent mirror 41, the mirror 42 and the semi-transparent mirror 41 are arranged in parallel, and the second mirror group 50 is disposed on the optical path between the mirror 42 and the semi-transparent mirror 41.

[0049] The light transmission radius of the second mirror group 50 is smaller than that of the reflector 42, and the light transmission radius of the second mirror group 50 is smaller than that of the semi-transparent and semi-reflective mirror 41.

[0050] In one embodiment, the second lens group 50 includes a fourth meniscus lens 52 and a biconvex lens 51. The concave surface of the fourth meniscus lens 52 with a large curvature is cemented to the convex surface of the biconvex lens 51, and the convex surface of the fourth meniscus lens 52 with a small curvature receives the reflected light from the reflecting mirror 42.

[0051] In one embodiment, the fourth meniscus lens 52 has a positive optical power, and the biconvex lens 51 has a negative optical power.

[0052] like Figure 1 As shown, the reflector 42 is disposed on the side of the variable aperture 30 opposite to the first meniscus lens 13.

[0053] It is understood that the reflector 42 reflects the light projected from the variable aperture 30 by 90° so as to project the light onto the semi-transparent mirror 41, thereby reducing the system volume by folding the optical path space.

[0054] Meanwhile, by adjusting the distance and reflection angle between the variable aperture 30 and the reflector 42, accurate imaging on the second mirror group 50 is ensured, light energy loss is avoided, and the uniform distribution of the light beam is maintained during the reflection process of the reflector 42.

[0055] like Figure 2 As shown, the light transmission radius of the reflector 42 is 22.24 mm, which facilitates the complete reflection of light passing through the variable aperture 30. The light transmission radius of 22.24 mm provides sufficient residual light, avoids the edge light from being blocked, and ensures the integrity of the reflected light.

[0056] The semi-transparent and semi-reflective mirror 41 is configured to receive the light beam reflected from the reflector 42 and split the light beam.

[0057] It is understood that the semi-transparent mirror 41 reflects the light beam and illuminates the illumination surface perpendicularly, thereby forming a coaxial illumination optical path, ensuring that the light beam coincides with the optical axis of the objective lens, eliminating shadows, while the light beam of the objective lens imaging is used for observation through the semi-transparent mirror 41 to avoid obstruction and achieve separation of the illumination and imaging optical paths.

[0058] It is understandable that the design of the reflector 42 and the semi-transparent mirror 41 not only reduces the size of the system, but also allows the light to be directly reflected and evenly irradiated onto the lighting surface through the semi-transparent mirror 41.

[0059] like Figure 2 As shown, the light transmission radius of the semi-transparent and semi-reflective mirror 41 is 21.15, so that the light reflected by the semi-transparent and semi-reflective mirror 41 can completely cover the object surface illumination target, ensuring the uniformity of illumination.

[0060] The light transmission radius of the fourth meniscus lens 52 and the biconvex lens 51 gradually decreases to adapt to the aperture of the beam reflected from the reflector 42, thereby achieving full reception of light from large NA fiber optic light sources.

[0061] Moreover, through such Figure 2 As shown, the radius of curvature of the side of the fourth meniscus lens 52 facing the reflecting mirror 42 is -79.31 mm, the radius of curvature of the cemented surface of the fourth meniscus lens 52 and the biconvex lens 51 is -33.33 mm, and the radius of curvature of the side of the biconvex lens 51 facing the semi-transparent mirror 41 is -87.24 mm. This is to correct the spherical aberration and chromatic aberration that were not completely eliminated by the second meniscus lens 11, the third meniscus lens 12, and the first meniscus lens 13, thereby improving the clarity of the image.

[0062] Meanwhile, the second mirror group optimizes the beam propagation path to ensure that the light uniformly covers the light transmission area of ​​the subsequent semi-transparent and semi-reflective mirror 41, avoiding edge light loss.

[0063] In one embodiment, an objective lens 60 is provided in the reflected light path of the semi-transparent mirror 41 to project light onto the illumination surface 70.

[0064] It is understood that the light beam reflected by the semi-transparent mirror 41 is perpendicularly and uniformly illuminating the illumination surface, while the objective lens receives the light reflected from the illumination surface. The imaging light of the objective lens is transmitted to the sensor through the semi-transparent mirror 41, thereby achieving the coincidence of the illumination and imaging optical axes.

[0065] The present invention also proposes an optical inspection device, which includes the coaxial illumination system compatible with large NA and large aperture optical fibers. The specific structure of the coaxial illumination system compatible with large NA and large aperture optical fibers is as described in the above embodiments. Since the present optical inspection device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0066] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A coaxial illumination system compatible with large-aperture optical fibers with large field of view (NA), characterized in that, include: The first lens group has a light source on one side; A reflector assembly, wherein the first mirror assembly faces the incident mirror surface of the reflector assembly, and an illumination surface is provided on the exit mirror surface side of the reflector assembly, and a second mirror assembly is provided between the incident mirror surface and the exit mirror surface; The light transmission radius of the first mirror group, the light transmission radius of the reflector group, and the light transmission radius of the second mirror group are all positively correlated with the numerical aperture of the optical fiber. The first mirror group includes a first cemented mirror and a first meniscus lens. After the light source enters the first cemented mirror, it passes through the first meniscus lens and the incident mirror surface before entering the reflector group. A variable aperture is provided between the first meniscus lens and the reflector group. The first cemented lens includes a second meniscus lens and a third meniscus lens, and the light transmission radius of the second meniscus lens, the third meniscus lens and the first meniscus lens gradually increase.

2. The coaxial illumination system compatible with large-aperture optical fibers with large NA as described in claim 1, characterized in that, The first meniscus lens has a positive optical power, the curvature of the side of the first meniscus lens facing the variable aperture is greater than the curvature of the side of the first meniscus lens away from the variable aperture, and the convex surface of the first meniscus lens faces the variable aperture.

3. The coaxial illumination system compatible with large-aperture, large-NA optical fibers as described in claim 2, characterized in that, The convex surface of the second meniscus lens is bonded to the concave surface of the third meniscus lens, with the convex surface of the third meniscus lens facing the first meniscus lens and the concave surface of the second meniscus lens facing the light source.

4. The coaxial illumination system compatible with large-aperture optical fibers with large NA as described in claim 3, characterized in that, The second meniscus lens has a positive optical power, the third meniscus lens has a negative optical power, and the curvature of the third meniscus lens facing the first meniscus lens is greater than the curvature of the second meniscus lens facing the light source.

5. The coaxial illumination system compatible with large-aperture, large-NA optical fibers as described in claim 3, characterized in that, The light transmission radius of the first meniscus lens is larger than that of the third meniscus lens, and the light transmission radius of the first meniscus lens is larger than that of the second meniscus lens.

6. The coaxial illumination system compatible with large-aperture, large-NA optical fibers as described in claim 3, characterized in that, The mirror assembly includes a mirror and a semi-transparent mirror, the mirror and the semi-transparent mirror are arranged in parallel, and the second mirror assembly is arranged on the optical path between the mirror and the semi-transparent mirror; Wherein, the light transmission radius of the second mirror group is smaller than that of the reflector, and the light transmission radius of the second mirror group is smaller than that of the semi-transparent and semi-reflective mirror.

7. The coaxial illumination system compatible with large-aperture, large-NA optical fibers as described in claim 6, characterized in that, The second lens group includes a fourth meniscus lens and a biconvex lens. The concave surface of the fourth meniscus lens with a large curvature is cemented to the convex surface of the biconvex lens, and the convex surface of the fourth meniscus lens with a small curvature receives the light reflected by the mirror.

8. The coaxial illumination system compatible with large-aperture optical fibers with large NA as described in claim 7, characterized in that, The fourth meniscus lens has a positive optical power, while the biconvex lens has a negative optical power.

9. The coaxial illumination system compatible with large-aperture, large-NA optical fibers as described in claim 6, characterized in that, An objective lens is provided in the reflected light path of the semi-transparent mirror to project light onto the illumination surface.

10. An optical inspection device, characterized in that, The coaxial illumination system includes any one of claims 1 to 9 that is compatible with large-aperture optical fibers with large NA.

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