A high-resolution printing inspection microscope objective

Abstract

This invention relates to a high-resolution printing inspection microscope objective, comprising a first lens, a second lens, an aperture, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical axis. An incident light beam is converged by the first lens, diverged by the second lens, its path is limited by the aperture, then diverged by the third lens, diverged by the fourth lens, converged by the fifth lens, and finally converged by the sixth lens to form an image on the extension of the optical axis. The high-resolution printing inspection microscope objective of this invention features long object distance and apochromatic characteristics, resulting in ideal and stable imaging.

Description

Technical Field

[0001] This invention relates to the field of optical lenses, and more particularly to a high-resolution printing inspection microscope objective. Background Technology

[0002] Microscope objectives, as key components of high-precision printing inspection equipment, are widely used in important processes such as product failure analysis and quality control. Compared to traditional photographic objectives, microscope objectives offer higher resolution, enabling rapid and clear localization of minute defects in the object under test. This not only allows for rigorous quality control but also significantly improves inspection efficiency and accuracy. Therefore, high-resolution microscope objectives are a strong guarantee of the effectiveness and reliability of printing inspection equipment.

[0003] Currently, with the rapid development of the printing industry, higher requirements are being placed on the accuracy and efficiency of printing quality inspection. However, existing microscope objectives still have shortcomings such as short object distance and imperfect color difference correction, which limit their application in high-precision printing inspection. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a high-resolution printing inspection microscope objective lens, which has advantages such as long object distance, apochromatic aberration, high resolution, and high imaging quality. The MTF of the entire field of view at a spatial frequency of 600 lp / mm is greater than 0.2, and the RMS blur spot size of each field of view is smaller than the Airy disk size. The total length of the lens is less than 55 mm.

[0005] This invention specifically relates to a high-resolution printing inspection microscope objective, comprising: a first lens with positive optical power and concave surface facing the image plane, arranged sequentially along the optical axis from the object side to the image side; a second lens with negative optical power and convex surface facing the object plane; a third lens with negative optical power composed of the first and second sub-lenses; a fourth lens with negative optical power composed of the third and fourth sub-lenses; a fifth lens with positive optical power and a biconvex surface; and a sixth lens with positive optical power and concave surface facing the image plane; wherein the third and fourth lenses are both... It is a cemented doublet lens; the optical power of the first lens is Φ1, the optical power of the second lens is Φ2, the optical power of the third lens is Φ3, the optical power of the fourth lens is Φ4, the optical power of the fifth lens is Φ5, the optical power of the sixth lens is Φ6, and the optical power of the entire microscope objective is Φ, which satisfies the following relationship: 0.5≤Φ≤0.1; wherein, the total optical length of the microscope objective, i.e., TTL≤55mm, and the optical power Φ1 of the first lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.56≤Φ1 / Φ≤0.64.

[0006] Furthermore, the optical power Φ2 of the second lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.74≤Φ2 / Φ≤-0.53.

[0007] Furthermore, the optical power Φ3 of the third lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.42≤Φ3 / Φ≤-0.2.

[0008] Furthermore, the optical power Φ4 of the fourth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.1≤Φ4 / Φ≤-0.056.

[0009] Furthermore, the optical power Φ5 of the fifth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.74≤Φ5 / Φ≤1.05.

[0010] Furthermore, the optical power Φ6 of the sixth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.12≤Φ6 / Φ≤0.25.

[0011] Furthermore, the refractive index of the first sub-lens is n. 31 The refractive index of the second sub-lens is n 32 The following relationship is satisfied: 0.04 ≤ |n 31 -n 32 |≤0.1.

[0012] Furthermore, the refractive index of the third sub-lens is n3, and the refractive index of the fourth sub-lens is n4, satisfying the following relationship: 0.12≤|n3-n4|≤0.3.

[0013] Furthermore, the Abbe number of the first sub-lens is Vd31, and the Abbe number of the second sub-lens is Vd32, satisfying the following relationship: 23≤|Vd31-Vd32|≤45.

[0014] Furthermore, the Abbe number of the third sub-lens is Vd41, and the Abbe number of the fourth sub-lens is Vd42, satisfying the following relationship: 35≤|Vd41-Vd42|≤40.

[0015] The high-resolution printing inspection microscope objective provided by this invention consists of only six groups (eight) of lenses, with a simple and easy-to-implement structure, and features long object distance and apochromatic characteristics. With the above-described structure, the high-resolution printing inspection microscope objective can achieve high-resolution full-field imaging, with the root mean square speckle of confusion in each field of view smaller than the Airy disk, resulting in ideal and stable imaging. It also ensures that the MTF (modulation transfer function) remains greater than 0.2 at a spatial frequency of 600 lp / mm, making it suitable for detecting fine defects in printed materials and providing strong technical support for high-precision printing inspection.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0018] Figure 1 A schematic diagram of the structure of the high-resolution printed inspection microscope objective lens of the present invention is shown;

[0019] Figure 2 A parameter table for a high-resolution printed inspection microscope objective according to an embodiment of the present invention is shown;

[0020] Figure 3 A schematic diagram of the diffusion spot and Airy spot corresponding to the high-resolution printed inspection microscope objective lens according to an embodiment of the present invention is shown.

[0021] Figure 4 The diagram shows the MTF value distribution of a high-resolution printed inspection microscope objective lens at different spatial frequencies according to an embodiment of the present invention.

[0022] Figure reference numerals: A1-First lens, A2-Second lens, A3-Third lens, A31-First sub-lens, A32-Second sub-lens, A4-Fourth lens, A41-Third sub-lens, A42-Fourth sub-lens, A5-Fifth lens, A6-Sixth lens, B1-Optical axis, B2-Aperture stop, B3-Image point, S1-Object plane of the first lens, S2-Image plane of the first lens, S3-Object plane of the second lens, S4-Image plane of the second lens, S5- Aperture plane, S6 - object plane of the first sub-lens, S7 - image plane of the first sub-lens, S8 - object plane of the second sub-lens, S9 - image plane of the second sub-lens, S10 - object plane of the third sub-lens, S11 - image plane of the third sub-lens, S12 - object plane of the fourth sub-lens, S13 - image plane of the fourth sub-lens, S14 - object plane of the fifth lens, S15 - image plane of the fifth lens, S16 - object plane of the sixth lens, S17 - image plane of the sixth lens, S18 - imaging plane. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, not all of them. The following embodiments are only for more clearly illustrating the technical solutions of the present invention and should not be used to limit the scope of protection of the present invention.

[0024] In the following description, the shape (convex or concave) of the lens element surface is defined as viewed from the corresponding side (i.e., from the object side or from the image side).

[0025] In the embodiments disclosed in this invention, the high-resolution printing inspection microscope objective lens, arranged sequentially from the object side to the image side, includes: a first lens A1 with positive optical power and concave surface facing the image plane, arranged along the optical axis B1; a second lens A2 with negative optical power and convex surface facing the object plane; a third lens A3 with negative optical power composed of a first sub-lens A31 and a second sub-lens A32; a fourth lens A4 with negative optical power composed of a third sub-lens A41 and a fourth sub-lens A42; a fifth lens A5 with positive optical power and biconvex surface; and a sixth lens A6 with positive optical power and concave surface facing the image plane; wherein the third lens A3 and the fourth lens A4 are both cemented doublet lenses.

[0026] The incident beam is converged by the first lens A1, diverged by the second lens A2, and then its path is limited by the aperture B2. It is then diverged by the third lens A3, diverged by the fourth lens A4, converged by the fifth lens A5, and finally converged by the sixth lens A6 to form an image at the imaging point B3 on the extension line of the optical axis B1, thus achieving high-resolution, apochromatic full-field imaging.

[0027] In a preferred embodiment, such as Figure 1 As shown, the first lens A1, the second lens A2, and the sixth lens A6 are all meniscus lens elements.

[0028] In a preferred embodiment, such as Figure 1 As shown, the first sub-lens A31 has a concave object surface S6 and a concave image surface S7 and has negative optical power; the second sub-lens A32 has a convex object surface S8 and a convex image surface S9 and has positive optical power. A third lens A3 with negative optical power is formed by cementing the first sub-lens A31 and the second sub-lens A32 together. Similarly, the third sub-lens A41 has a flat object surface S10 and a concave image surface S11 and has negative optical power; the fourth sub-lens A42 has a convex object surface S12 and a convex image surface S12 and has positive optical power. A fourth lens A4 with negative optical power is formed by cementing the third sub-lens A41 and the fourth sub-lens A42 together. These two sets of negative optical power cemented doublets, combined with the design of each sub-lens, help eliminate chromatic aberration, reduce reflection loss, and improve image quality. They also simplify the assembly process and reduce the size and weight of the optical components.

[0029] In a preferred embodiment, such as Figure 1 As shown, an aperture stop B2 is provided between the second lens A2 and the third lens A3; preferably, the distance between the aperture stop B2 and the second lens A2 is greater than or equal to three times the distance between the aperture stop B2 and the third lens A3, so as to control the incident light and further eliminate chromatic aberration.

[0030] In addition, the high-resolution printing inspection microscope objective also includes an optional light-transmitting window (not shown) arranged between the image plane S17 and the imaging plane S18 of the sixth lens A6 for imaging the object. Optionally, an image sensor is arranged at the imaging plane S18 for imaging, or an eyepiece is arranged after the imaging plane S18 for further magnification and image processing.

[0031] The total optical length (TTL) of the lens assembly is defined as the distance between the object plane and the imaging plane of the first lens on the optical axis. In all embodiments disclosed in this invention, the total optical length (TTL) of the lens assembly is ≤55mm.

[0032] In the specific embodiments disclosed in this invention, the optical power of the first lens is Φ1, the optical power of the second lens is Φ2, the optical power of the third lens is Φ3, the optical power of the fourth lens is Φ4, the optical power of the fifth lens is Φ5, the optical power of the sixth lens is Φ6, and the optical power of the entire microscope objective is Φ.

[0033] In a preferred embodiment, the optical power of the entire microscope objective is Φ, which satisfies 0.5≤Φ≤0.1.

[0034] In a preferred embodiment, the optical power Φ1 of the first lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.56≤Φ1 / Φ≤0.64.

[0035] In a preferred embodiment, the optical power Φ2 of the second lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.74≤Φ2 / Φ≤-0.53.

[0036] In a preferred embodiment, the optical power Φ3 of the third lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.42≤Φ3 / Φ≤-0.2.

[0037] In a preferred embodiment, the optical power Φ4 of the fourth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.1≤Φ4 / Φ≤-0.056.

[0038] In a preferred embodiment, the optical power Φ5 of the fifth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.74≤Φ5 / Φ≤1.05.

[0039] In a preferred embodiment, the optical power Φ6 of the sixth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.12≤Φ6 / Φ≤0.25.

[0040] In a preferred embodiment, the refractive index of the first sub-lens is n. 31 The refractive index of the second sub-lens is n 32The following relationship is satisfied: 0.04 ≤ |n 31 -n 32 |≤0.1; Preferably, the Abbe number of the first sub-lens is Vd 31 The Abbe number of the second sub-lens is Vd. 32 The following relationship is satisfied: 23≤|Vd 31 -Vd 32 |≤45. By setting relative refractive index relationships and different Abbe numbers, aberrations in the front optical path are corrected and controlled, while the beam diffusion angle is adjusted.

[0041] In a preferred embodiment, the refractive index of the third sub-lens is n3, and the refractive index of the fourth sub-lens is n4, satisfying the following relationship: 0.12 ≤ |n3 - n4| ≤ 0.3; preferably, the Abbe number of the third sub-lens is Vd. 41 The Abbe number of the fourth sub-lens is Vd. 42 The following relationship is satisfied: 35≤|Vd 41 -Vd 42 |≤40. By setting relative refractive index relationships and different Abbe numbers, aberrations in the front optical path are corrected and controlled, while the beam diffusion angle is adjusted.

[0042] The following provides a specific embodiment of the present invention and its performance effects as an auxiliary illustration:

[0043] The structure of the high-resolution printed inspection microscope objective in this embodiment is shown in [reference]. Figure 1 . Figure 2 The table below illustrates the specific parameter selections for each optical element in this embodiment. For ease of understanding, S0 represents the object being observed, and S18 represents the imaging plane (i.e., the image plane in the table). The first column of the table lists the optical surfaces of each optical element from S1 to S17, which sequentially form the optical path of the objective lens; the second column shows the radius of curvature corresponding to that surface, and the third column shows the distance between that surface and the next surface (defined on the optical axis B1), all in millimeters (mm).

[0044] Furthermore, columns four and five of the table list the refractive index and Abbe number of the material used in the optical element (if it is a lens) containing that surface, respectively. These parameters are crucial for adjusting the refractive properties of optical elements, eliminating chromatic aberration, and optimizing image quality. By appropriately selecting and combining the refractive index and Abbe number of these materials, ideal beam refraction effects can be achieved in the optical system, thereby improving the imaging accuracy and resolution of the objective lens.

[0045] In a preferred embodiment, the distance (5.99 mm) between the second lens A2 and the third lens A3 (the air gap between the object plane S4 and the image plane S6) is greater than 1 / 10 of the TTL (55 mm). More preferably, the distance (18.53 mm) between the third lens A3 and the sixth lens A6 (i.e., between the object plane S7 and the image plane S16) is less than 2 / 5 of the TTL (55 mm).

[0046] By setting the aforementioned distances, it can be further ensured that the size of the blur spot of the microscope objective is smaller than the Airy disk size in all fields of view. It is worth noting that the object distance (i.e., the distance from S0 to S1) can be approximated as infinite in this embodiment. This indicates that this high-resolution printing inspection microscope objective has a long object distance characteristic, enabling effective imaging at greater object distances, which is crucial for improving inspection accuracy and ensuring image quality. The long object distance characteristic allows this objective to adapt to the measurement needs of more practical applications, especially in fields requiring high resolution, such as printing inspection, where it exhibits significant advantages.

[0047] Through these precise parameter selections and optimized designs, the high-resolution printing inspection microscope objective lens of this embodiment possesses excellent imaging performance, demonstrating superior performance in capturing minute details, controlling chromatic aberration, and correcting aberrations, fully meeting the requirements of high-precision microscope imaging.

[0048] Figure 3 The diagram illustrates the blur and Airy disk corresponding to a slight change in the distance to the imaging plane S18 of the high-resolution printed inspection microscope objective in this embodiment. The black circles in the diagram represent the size of the system's Airy disk. When the diameter of the blur is smaller than the diameter of the Airy disk, the optical system is considered to have excellent imaging quality, indicating that it is an ideal optical system. Figure 3 As can be seen, even with a significant shift in the imaging plane S18, the diffuse spots of different colors of light remain highly stable and consistently concentrated within the Airy disk region. This indicates that the aberrations of the optical system have been largely corrected, ensuring high stability and accuracy in imaging. Comparison reveals that the diffuse spots in all fields of view are smaller than the Airy disk for both short-wavelength and long-wavelength light, demonstrating the system's excellent imaging capability for different wavelengths of light. The consistent and stable imaging quality for different colors of light verifies the superior imaging performance of this high-resolution printed inspection microscope objective in practical applications.

[0049] Figure 4 This paper presents the modulation transfer function (MTF) value distribution of the high-resolution printing inspection microscope objective at different spatial frequencies. Figure 4 In the diagram, the vertical axis is marked with the OTF (Optical Frequency Tolerance) value, or MTF, which reflects the contrast variation of an optical system when transmitting spatial frequencies and is commonly used to measure the resolution of an imaging system. According to... Figure 4As can be seen, the MTF value gradually decreases with increasing spatial frequency, because details at higher frequencies typically become blurred during imaging. In this embodiment, the high-resolution printing inspection microscope objective maintains an MTF value greater than 0.2 even at spatial frequencies up to 600.0 lp / mm. Therefore, when capturing very small defects or details, the high-resolution printing inspection microscope objective of this embodiment still provides clear and high-contrast imaging, exhibiting excellent resolution and detail capture capabilities, making it particularly suitable for detecting minute defects or other fine structures in printed materials.

[0050] pass Figure 3 and Figure 4 The analysis shows that the high-resolution printing inspection microscope objective of this embodiment performs excellently in terms of imaging accuracy, aberration correction, and resolution. Whether dealing with minute defects on the surface of an object or complex situations requiring high spatial frequency imaging, this objective can provide high-quality and stable imaging, ensuring the high performance and reliability of the system.

[0051] Notice, Figure 2 The table does not imply that embodiments of the present invention are limited to the parameter selection in this scheme. According to other embodiments of the present invention, parameters can be reasonably adjusted within a given range to achieve [the desired effect]. Figure 3 , Figure 4 The similar technical effects shown are evident. Therefore, the specific parameters and design details of each optical element are not fixed, but can be optimized within a specified range.

[0052] Furthermore, the optical elements of this invention can be fixedly housed within a one-piece molded housing to ensure the stability and precision of the optical system. The one-piece molded housing effectively prevents the optical elements from shifting due to external vibrations or impacts, thus ensuring that the entire optical system maintains precise alignment and performance throughout operation. The housing design not only offers structural compactness but also optimizes the distance and arrangement between optical elements, reducing unnecessary errors and interference in the optical path and improving image quality.

[0053] Alternatively, the layout and adjustments can be made in other reasonable ways. For example, optical elements can be connected to mechanical components, which, through precise adjustment mechanisms, allow for fine-tuning of each optical element during operation. This design allows for meticulous control of each component of the optical system, enabling adaptive adjustments based on different needs and environmental conditions in practical use. Simultaneously, the aperture size can be dynamically adjusted. By controlling the aperture size, the intensity of the incident beam can be flexibly adjusted, further optimizing the imaging effect, especially when dealing with different lighting conditions or changes in the working environment, ensuring the system is always in optimal working condition.

[0054] By properly configuring and adjusting these components, not only can the excellent performance of the optical system be maintained, but it can also be flexibly adapted to the specific requirements of different application scenarios. For example, under different light intensities, temperatures, or humidity conditions, the system can still maintain its high precision and stability, meeting the needs of a wide range of applications for high-resolution, accurate imaging.

[0055] It should be emphasized that the embodiments described in this invention are exemplary, not limiting. Therefore, this invention is not limited to the embodiments described in the specific implementation. Any other implementation methods derived by those skilled in the art based on the technical solutions of this invention also fall within the scope of protection of this invention.

Claims

1. A high-resolution printed inspection microscope objective, characterized in that, include: Arranged sequentially along the optical axis (B1) from the object side to the image side are: a first lens (A1) with positive optical power and concave surface facing the image plane; a second lens (A2) with negative optical power and convex surface facing the object plane; a third lens (A3) with negative optical power composed of a first sub-lens (A31) and a second sub-lens (A32); a fourth lens (A4) with negative optical power composed of a third sub-lens (A41) and a fourth sub-lens (A42); a fifth lens (A5) with positive optical power and biconvex surface; and a sixth lens (A6) with positive optical power and concave surface facing the image plane. The first sub-lens (A31) has a concave object surface and a concave image surface and has negative optical power; the second sub-lens (A32) has a convex object surface and a convex image surface and has positive optical power; the third sub-lens (A41) has a flat object surface and a concave image surface and has negative optical power; and the fourth sub-lens (A42) has a convex object surface and a convex image surface and has positive optical power. Both the third lens (A3) and the fourth lens (A4) are cemented doublet lenses; The optical power of the first lens is Φ1, the optical power of the second lens is Φ2, the optical power of the third lens is Φ3, the optical power of the fourth lens is Φ4, the optical power of the fifth lens is Φ5, the optical power of the sixth lens is Φ6, and the optical power of the entire microscope objective is Φ, satisfying the following relationship: 0.1≤Φ≤0.5; Wherein, the total optical length of the microscope objective is TTL≤55mm, and the optical power Φ1 of the first lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.56≤Φ1 / Φ≤0.

64.

2. The high-resolution printed inspection microscope objective according to claim 1, characterized in that, The optical power Φ2 of the second lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.74≤Φ2 / Φ≤-0.

53.

3. The high-resolution printed inspection microscope objective lens according to claim 1, characterized in that, The optical power Φ3 of the third lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.42≤Φ3 / Φ≤-0.

2.

4. The high-resolution printed inspection microscope objective lens according to claim 1, characterized in that, The optical power Φ4 of the fourth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: -0.1≤Φ4 / Φ≤-0.

056.

5. The high-resolution printed inspection microscope objective lens according to claim 1, characterized in that, The optical power Φ5 of the fifth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.74≤Φ5 / Φ≤1.

05.

6. The high-resolution printed inspection microscope objective according to claim 1, characterized in that, The optical power Φ6 of the sixth lens and the optical power Φ of the entire microscope objective satisfy the following relationship: 0.12≤Φ6 / Φ≤0.

25.

7. The high-resolution printed inspection microscope objective according to any one of claims 1-6, characterized in that, The refractive index of the first sub-lens is n 31 The refractive index of the second sub-lens is n 32 The following relationship is satisfied: 0.04 ≤ |n 31 -n 32 |≤0.

1.

8. The high-resolution printed inspection microscope objective according to any one of claims 1-6, characterized in that, The refractive index of the third sub-lens is n3, and the refractive index of the fourth sub-lens is n4, satisfying the following relationship: 0.12≤|n3-n4|≤0.

3.

9. The high-resolution printed inspection microscope objective according to any one of claims 1-6, characterized in that, The Abbe number of the first sub-lens is Vd 31 The Abbe number of the second sub-lens is Vd. 32 The following relationship is satisfied: 23≤|Vd 31 -Vd 32 |≤45.

10. The high-resolution printed inspection microscope objective according to any one of claims 1-6, characterized in that, The Abbe number of the third sub-lens is Vd. 41 The Abbe number of the fourth sub-lens is Vd. 42 The following relationship is satisfied: 35≤|Vd 41 -Vd 42 |≤40.

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