High-resolution printing detection microscope objective lens

Abstract

The invention relates to a high-resolution printing detection microscope objective lens, which comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged along an optical axis, and is characterized in that an incident beam is converged by the first lens and diverged by the second lens in sequence, and then the path of the incident beam is limited by the diaphragm; and then the light is diverged by the third lens, diverged by the fourth lens and converged by the fifth lens in sequence, and is finally converged by the sixth lens to be imaged on an extension line of the optical axis. The high-resolution printing detection microscope objective lens has a long object distance and apochromatic characteristics, and the imaging condition is ideal and stable.

Description

Technical Field

[0001] The invention relates to the field of optical lenses, and in particular to a high-resolution printing detection microscope objective lens. Background Art

[0002] Microscope objective lenses are key components of high-precision printing inspection equipment and are widely used in important links such as product failure analysis and quality control. Compared with traditional photographic objective lenses, microscope objective lenses have higher resolution and can quickly and clearly locate tiny defects in the object being tested. They can not only strictly control the quality of products, but also significantly improve the efficiency and accuracy of inspection. Therefore, high-resolution microscope objective lenses are a strong guarantee for measuring the effectiveness and reliability of printing inspection equipment.

[0003] At present, with the rapid development of the printing industry, higher requirements are put forward for the detection accuracy and efficiency of printing quality. However, the existing microscope objective lenses still have shortcomings such as short object distance and imperfect chromatic aberration correction, which limits their application in high-precision printing detection. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a high-resolution printing inspection microscope objective lens, which has the advantages of long object distance, apochromatism, high resolution, high imaging quality, etc. The MTF of the entire field of view at a spatial frequency of 600lp / mm is greater than 0.2, and the RMS diffusion spot size of each field of view is smaller than the Airy disk size, and the total length of the lens is less than 55mm.

[0005] The present invention specifically relates to a high-resolution printing inspection microscope objective lens, comprising: a first lens with positive focal power and a concave surface facing the image surface, which are arranged in sequence from the object side to the image side along the optical axis, a second lens with negative focal power and a convex surface facing the object surface, a third lens with negative focal power composed of a first sub-lens and a second sub-lens, a fourth lens with negative focal power composed of a third sub-lens and a fourth sub-lens, a fifth lens with positive focal power and a biconvex surface, and a sixth lens with positive focal power and a concave surface facing the image surface; the third lens and the fourth lens are both It is a double cemented lens; the optical focal power of the first lens is Φ1, the optical focal power of the second lens is Φ2, the optical focal power of the third lens is Φ3, the optical focal power of the fourth lens is Φ4, the optical focal power of the fifth lens is Φ5, the optical focal power of the sixth lens is Φ6, and the optical focal 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 focal power Φ1 of the first lens and the optical focal power Φ of the entire microscope objective satisfy the following relationship: 0.56≤Φ1 / Φ≤0.64.

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

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

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

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

[0010] Furthermore, the focal power Φ6 of the sixth lens and the focal power Φ of the entire microscope objective lens 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 , satisfying the following relationship: 0.04≤|n 31 -n 32 |≤0.1.

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

[0013] Further, 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 the present invention is composed of only six groups (eight) of lenses, has a simple structure, is easy to implement, and has long object distance and apochromatic characteristics. Through the high-resolution printing inspection microscope objective of the above structure, high-resolution full-field imaging can be achieved, the root mean square dispersion spot of each field of view is smaller than the Airy disk, and the imaging is ideal and stable; at a spatial frequency of 600lp / mm, the MTF (modulation transfer function) is still greater than 0.2, which is suitable for detecting fine defects in printed products and provides a strong technical guarantee for high-precision printing inspection.

[0016] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 1 The schematic diagram of the structure of the high-resolution printing inspection microscope objective lens of the present invention is shown; Figure 2 A parameter table of a high-resolution printing inspection microscope objective lens according to an embodiment of the present invention is shown; Figure 3 A schematic diagram showing a diffuse spot and an Airy disk corresponding to a high-resolution printing inspection microscope objective lens according to an embodiment of the present invention is shown; Figure 4 The figure shows the distribution diagram of MTF values ​​of a high-resolution printing inspection microscope objective lens at different spatial frequencies according to one embodiment of the present invention.

[0019] 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, B3-imaging 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 DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings: the described embodiments are only part of the 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 cannot be used to limit the scope of protection of the present invention.

[0021] In the following description, the shape (convex or concave) of the surface of a lens element is defined as viewed from the corresponding side (ie, viewed from the object side or from the image side).

[0022] In the embodiment disclosed in the present invention, in order from the object side to the image side, the high-resolution printing inspection microscope objective lens includes: a first lens A1 with positive focal power and a concave surface facing the image plane, arranged in sequence along the optical axis B1, a second lens A2 with negative focal power and a convex surface facing the object plane, a third lens A3 with negative focal power composed of a first sub-lens A31 and a second sub-lens A32, a fourth lens A4 with negative focal power composed of a third sub-lens A41 and a fourth sub-lens A42, a fifth lens A5 with positive focal power and a biconvex surface, and a sixth lens A6 with positive focal power and a concave surface facing the image plane; wherein the third lens A3 and the fourth lens A4 are both double-cemented lenses.

[0023] The incident light beam is converged by the first lens A1 and diverged by the second lens A2, and then the path is limited by the aperture B2. Then, the light beam is 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 be imaged at the imaging point B3 on the extension line of the optical axis B1, thereby achieving high-resolution, achromatic full-field imaging.

[0024] In a preferred embodiment, Figure 1 As shown, the first lens A1, the second lens A2 and the sixth lens A6 are all meniscus lens elements.

[0025] In a preferred embodiment, Figure 1 As shown, the first sub-lens A31 has a concave object surface S6 and a concave image surface S7 and has negative focal power, the second sub-lens A32 has a convex object surface S8 and a convex image surface S9 and has positive focal power, and the first sub-lens A31 and the second sub-lens A32 are glued together to form a third lens A3 with negative focal power; the third sub-lens A41 has a flat object surface S10 and a concave image surface S11 and has negative focal power, the fourth sub-lens A42 has a convex object surface S12 and a convex image surface S12 and has positive focal power, and the third sub-lens A41 and the fourth sub-lens A42 are glued together to form a fourth lens A4 with negative focal power. Two groups of double glued lenses with negative focal power, in conjunction with the design of each sub-lens, help eliminate chromatic aberration, reduce reflection loss, and improve imaging quality, while also simplifying the assembly process and reducing the volume and weight of optical components.

[0026] In a preferred embodiment, Figure 1 As shown, an aperture B2 is provided between the second lens A2 and the third lens A3; preferably, the distance between the aperture B2 and the second lens A2 is greater than or equal to three times the distance between the aperture B2 and the third lens A3, so as to control the incident light and further eliminate chromatic aberration.

[0027] In addition, the high-resolution printing inspection microscope objective lens 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 behind the imaging plane S18 to further magnify and process the image.

[0028] 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 the present invention, the total optical length TTL of the lens assembly is ≤55 mm.

[0029] In the specific embodiment disclosed in the present invention, the optical focal length of the first lens is Φ1, the optical focal length of the second lens is Φ2, the optical focal length of the third lens is Φ3, the optical focal length of the fourth lens is Φ4, the optical focal length of the fifth lens is Φ5, the optical focal length of the sixth lens is Φ6, and the optical focal length of the entire microscope objective is Φ.

[0030] In a preferred embodiment, the optical focal length of the entire microscope objective is Φ, which satisfies 0.5≤Φ≤0.1.

[0031] In a preferred embodiment, the focal power Φ1 of the first lens and the focal power Φ of the entire microscope objective lens satisfy the following relationship: 0.56≤Φ1 / Φ≤0.64.

[0032] In a preferred embodiment, the focal power Φ2 of the second lens and the focal power Φ of the entire microscope objective lens satisfy the following relationship: -0.74≤Φ2 / Φ≤-0.53.

[0033] In a preferred embodiment, the focal power Φ3 of the third lens and the focal power Φ of the entire microscope objective lens satisfy the following relationship: -0.42≤Φ3 / Φ≤-0.2.

[0034] In a preferred embodiment, the focal power Φ4 of the fourth lens and the focal power Φ of the entire microscope objective lens satisfy the following relationship: -0.1≤Φ4 / Φ≤-0.056.

[0035] In a preferred embodiment, the optical power Φ5 of the fifth lens and the optical power Φ of the entire microscope objective lens satisfy the following relationship: 0.74≤Φ5 / Φ≤1.05.

[0036] In a preferred embodiment, the focal power Φ6 of the sixth lens and the focal power Φ of the entire microscope objective lens satisfy the following relationship: 0.12≤Φ6 / Φ≤0.25.

[0037] 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 32, satisfying the following relationship: 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 , satisfying the following relationship: 23≤|Vd 31 -Vd 32 |≤45. By setting the relative refractive index relationship and different Abbe numbers, the aberration in the front optical path is corrected and controlled, and the diffusion angle of the light beam is adjusted.

[0038] 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 , satisfying the following relationship: 35≤|Vd 41 -Vd 42 |≤40. By setting the relative refractive index relationship and different Abbe numbers, the aberration in the front optical path is corrected and controlled, and the diffusion angle of the light beam is adjusted.

[0039] A specific embodiment of the present invention and its performance effects are provided below as auxiliary explanation: The structure of the high-resolution printing inspection microscope objective lens in this embodiment is shown in Figure 1 . Figure 2 The table in shows the specific parameter selection of each optical element in this embodiment. For ease of understanding, S0 represents the observation point in the table, and S18 represents the imaging surface (i.e., the image surface in the table). The first column of the table lists the optical surfaces of each optical element from S1 to S17, which in turn constitute the optical path of the objective lens; the second column shows the curvature radius corresponding to the surface, and the third column is the distance between the surface and the next surface (defined on the optical axis B1), all in millimeters (mm).

[0040] In addition, the fourth and fifth columns of the table list the refractive index and Abbe number of the material used in the optical element (if it is a lens) where the surface is located. These parameters are crucial for adjusting the refractive performance of optical elements, eliminating chromatic aberration, and optimizing imaging quality. By properly selecting and matching the refractive index and Abbe number of these materials, an ideal beam refraction effect can be achieved in the optical system, thereby improving the imaging accuracy and resolution of the objective lens.

[0041] 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 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 TTL (55 mm).

[0042] By setting the above distance, it can be further ensured that the diffuse spot size of the microscope objective lens in each field of view is smaller than the Airy disk size. It is worth noting that the object distance (i.e., the distance from S0 to S1) can be approximated to infinity in this embodiment. This shows that the high-resolution printing inspection microscope objective lens has a long object distance characteristic and can perform effective imaging at a longer object distance, which is crucial to improving detection accuracy and ensuring imaging quality. The long object distance characteristic enables the objective lens to adapt to measurement needs in more practical applications, especially in fields requiring high resolution such as printed product inspection, showing significant advantages.

[0043] Through these precise parameter selection and optimized design, the high-resolution printing inspection microscope objective lens of this embodiment has excellent imaging performance, and can excel in capturing tiny details, chromatic aberration control and aberration correction, etc., fully meeting the requirements of high-precision microscope imaging.

[0044] Figure 3 The figure shows the diffuse spots and Airy disks corresponding to the slight change in the distance of the imaging surface S18 of the objective lens of the high-resolution printing inspection microscope in this embodiment. The black circle in the figure represents the size of the Airy disk of the system. When the diffuse spot diameter of the optical system is smaller than the Airy disk diameter, it is considered that the imaging quality of the optical system is excellent, indicating that the optical system is an ideal optical system. Figure 3 It can be seen that even with a large offset of the imaging surface S18, the diffuse spots of different colors of light remain highly stable and are always concentrated in the area of ​​the Airy disk. This shows that the aberrations of the optical system have been greatly corrected, ensuring the high stability and accuracy of the imaging. By comparison, it can be found that whether it is short-wave light or long-wave light, the diffuse spots in each field of view are smaller than the Airy disk, indicating that the system has good imaging capabilities for light of different wavelengths, and the imaging quality of different colors of light is consistent and stable, verifying the excellent imaging performance of the high-resolution printing inspection microscope objective in actual use.

[0045] Figure 4 The distribution diagram of the modulation transfer function (MTF) value of the high-resolution printing inspection microscope objective lens at different spatial frequencies is shown. Figure 4 In the figure, the vertical axis is marked as OTF modulus, or MTF, which reflects the contrast change of the optical system when transmitting spatial frequency and is usually used to measure the resolution of the imaging system. Figure 4It can be seen that as the spatial frequency increases, the MTF value gradually decreases, because the details of higher frequencies usually become blurred during the imaging process. The MTF value of the high-resolution printing inspection microscope objective lens in this embodiment remains at a level greater than 0.2 at a spatial frequency of up to 600.0lp / mm. Therefore, when capturing very small defects or details, the high-resolution printing inspection microscope objective lens in this embodiment can still provide clear and high-contrast imaging effects, with excellent resolution and detail capture capabilities, and is particularly suitable for detecting small defects or other fine structures in printed products.

[0046] pass Figure 3 and Figure 4 From the analysis, it can be seen that the high-resolution printing inspection microscope objective lens of this embodiment performs well in imaging accuracy, aberration correction and resolution. Whether facing subtle defects on the surface of an object or complex situations requiring high spatial frequency imaging, the objective lens can provide high-quality and stable imaging, ensuring the high performance and reliability of the system.

[0047] Notice, Figure 2 The table does not mean that the embodiment of the present invention is limited to the parameter selection in this solution. According to other embodiments of the present invention, the parameters can be reasonably coordinated and adjusted within a given interval to achieve the same Figure 3 , Figure 4 Therefore, the specific parameters and design details of each optical element are not fixed, but can be optimized within a specified range.

[0048] In addition, the optical element of the present invention can be fixedly arranged in an integrally formed housing to ensure the stability and accuracy of the optical system. The use of an integrally formed housing can effectively prevent the position of the optical element from being shifted due to external vibration or impact, thereby ensuring that the entire optical system can always maintain precise alignment and performance during operation. The design of the housing is not only structurally compact, but also can reduce unnecessary errors and interference on the optical path by optimizing the distance and arrangement between optical elements, thereby improving the quality of imaging.

[0049] In addition, layout and adjustment can also be carried out in other reasonable ways. For example, optical components can be connected to mechanical components, and the mechanical components can be fine-tuned during operation through precise adjustment mechanisms. Such a design allows for detailed regulation of each component of the optical system, so that adaptive adjustments can be made according to different needs and environmental conditions in actual use. At the same time, the opening size of the diaphragm can also be adjusted dynamically. By controlling the size of the diaphragm, the intensity of the incident light beam can be flexibly adjusted to further optimize the imaging effect, especially when dealing with different lighting conditions or changes in the working environment, ensuring that the system is always in the best working state.

[0050] 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 intensity, temperature or humidity conditions, the system can still maintain its high accuracy and stability, meeting the needs of high-resolution and precise imaging in a wide range of application fields.

[0051] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the embodiments described in the specific implementation manners, and any other implementation manners derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

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

64.

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

53.

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

2.

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

056.

5. The high-resolution printing 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 lens satisfy the following relationship: 0.74≤Φ5 / Φ≤1.

05.

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

25.

7. The high-resolution printing inspection microscope objective lens according to any one of claims 1 to 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 , satisfying the following relationship: 0.04≤|n 31 -n 32 |≤0.

1.

8. The high-resolution printing inspection microscope objective lens according to any one of claims 1 to 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, which satisfy the following relationship: 0.12≤|n3-n4|≤0.

3.

9. The high-resolution printing inspection microscope objective lens according to any one of claims 1 to 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 , satisfying the following relationship: 23≤|Vd 31 -Vd 32 |≤45.

10. The high-resolution printing inspection microscope objective lens according to any one of claims 1 to 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 , satisfying the following relationship: 35≤|Vd 41 -Vd 42 |≤40.

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