A method for realizing super-resolution optical microscopic imaging based on deviation of objective lens optical axis from microscope main optical axis

Abstract

The application provides a method for realizing super-resolution optical microscopic imaging based on the deviation of an objective lens optical axis from a microscope main optical axis. The application proposes a method for realizing super-resolution imaging by using a conventional optical microscope without modification or addition of complicated equipment. By slightly adjusting the objective lens turntable angle, the objective lens optical axis and the microscope main optical axis form an included angle of 3-4 degrees, and the opening diameter of the aperture diaphragm is reduced, so that the resolution of the microscope is improved from about 300 nm to 100 nm. The method reasonably optimizes and utilizes the optical imaging conditions of the microscope itself, and is particularly suitable for high-resolution, real-time and non-destructive observation of the periodic linear array nanostructure on the sample surface. The method is simple in operation and low in cost, expands the application range of the conventional optical microscope, and has good practical value and application prospect in the fields of material microstructure analysis and semiconductor chip detection.

Description

Technical Field

[0001] This invention relates to the field of optical microscopy imaging technology, and in particular to a method for achieving super-resolution optical microscopy imaging based on the objective lens optical axis deviating from the principal optical axis of the microscope. Background Technology

[0002] Optical microscopes are among the most commonly used microscopic imaging tools, widely applied in materials science, biomedicine, semiconductors, and other fields. However, limited by the optical diffraction limit, the imaging resolution of conventional optical microscopes is typically confined to the 200-300 nm range, making it difficult to meet the demands for high-resolution imaging and analysis of the fine microstructures in samples. To overcome this limitation, researchers have developed various super-resolution optical microscopy techniques, including super-resolution fluorescence microscopy, near-field super-resolution imaging techniques, and structured illumination microscopy.

[0003] Super-resolution fluorescence microscopy techniques, such as stimulated emission depletion microscopy (STED), photoactivated localization microscopy (PALM), and stochastic optical reconstruction microscopy (STORM), utilize the controlled excitation and emission of fluorescent molecules to achieve super-resolution imaging of biological samples, with imaging resolutions reaching the 20 nm level. However, these techniques rely on fluorescent labeling of samples, are complex to operate, costly, and have stringent requirements on the experimental environment and the samples themselves, limiting their application in routine detection in fields such as materials science.

[0004] Near-field super-resolution imaging techniques, such as near-field scanning optical microscopy, microsphere superlenses, and solid immersion lenses, achieve super-resolution imaging of samples by introducing nanoscale optical elements on the sample surface to capture evanescent waves in the near-field region, with imaging resolutions on the order of 50-100 nm. However, these techniques typically require complex experimental setups and delicate manipulation, and their imaging speed is relatively slow or their field of view is limited, thus limiting their ability to perform high-throughput observations of large-area samples.

[0005] Structured illumination microscopy (SIM) projects periodic structured light onto a sample, utilizing the modulation of high-frequency information in the sample by optical fringes to achieve approximately twice the resolution of conventional microscopy, with imaging resolution reaching 100-120 nm. However, SIM requires high stability and precision of the optical system, resulting in relatively expensive equipment, and obtaining super-resolution images requires complex algorithm processing and image reconstruction.

[0006] Furthermore, dark-field microscopy and oblique illumination microscopy enhance the microscope's ability to image the fine structure of samples to some extent by employing special illumination methods. Dark-field microscopy utilizes a ring aperture or dark-field condenser to generate a centrally shielded ring illumination light, allowing the light to be incident on the sample surface at a relatively large tilt angle (usually 60-80°). The objective lens collects only the scattered light from the sample surface while filtering out background light, thus better highlighting the fine structure of the sample against a dark background. Oblique illumination microscopy introduces oblique baffles or off-center apertures into the microscope's illumination path, allowing the illumination light to be incident on the sample surface at a certain tilt angle (usually 5-45°), improving image resolution to some extent. However, limited by the optical diffraction limit, the improvement in imaging resolution by these two techniques is limited, making it difficult to truly achieve super-resolution imaging.

[0007] In summary, existing super-resolution microscopy techniques often rely on complex and expensive equipment, delicate manipulation, and cumbersome sample preparation, making it difficult to meet the daily needs of materials science for simple, rapid, low-cost, and high-resolution sample detection. Therefore, there is an urgent need to develop a novel super-resolution optical microscopy technique that requires no complex modifications to the microscope system, is easy to operate, and is inexpensive, in order to achieve efficient and real-time detection of the fine nanoscale structure of samples and truly meet the application needs of production practice. Summary of the Invention

[0008] This invention addresses the limitations of existing optical microscopy imaging techniques in characterizing nanostructures on sample surfaces by proposing a novel super-resolution imaging method based on conventional optical microscopes. This method optimizes the imaging optical path by precisely adjusting the relative angle between the objective lens optical axis and the microscope's principal optical axis, creating a slight deviation within the range of 3-4°. This overcomes the strict parallelism limitation of optical axes in classical microscopy imaging systems, effectively improving imaging resolution without introducing complex hardware, and achieving clear imaging of the fine nanoscale structures on sample surfaces.

[0009] The super-resolution optical microscopy imaging method of this invention is particularly suitable for samples with a large number of periodically arranged linear nanostructures on their surface, such as gate structures and photoresist patterns on semiconductor chip surfaces. The imaging resolution is optimally improved when the objective lens optical axis deviates from the microscope's principal optical axis by 3–4°, and the long axis of the periodic linear array structure is parallel to the vertical direction in the microscopic imaging field of view. With a suitable deflection angle and a small aperture diaphragm opening diameter, the method of this invention can improve the resolution of a conventional microscope from approximately 300 nm to the order of 100 nm, achieving a 2-fold resolution gain.

[0010] In conventional optical microscopes, the objective lens optical axis is usually strictly parallel or coaxial with the microscope's principal optical axis and the sample surface normal. While this optical path configuration is beneficial for obtaining clear images, it is difficult to achieve super-resolution imaging due to the diffraction limit. Recent advancements in tilt-illuminated microscopy techniques, such as tilt-plane illumination microscopy and light-panel illumination microscopy, have improved imaging performance to some extent through special illumination methods, but their objective lens optical axes remain parallel to the microscope's principal optical axis, failing to overcome the inherent limitations of conventional microscope optical paths.

[0011] Unlike existing tilting illumination techniques, this invention cleverly adjusts the angle between the objective lens optical axis and the microscope's principal optical axis, achieving non-collinearity of the optical axes within a small deflection range of 3–4°, breaking free from the constraints of traditional microscopic imaging optical path design. This novel optical axis deflection configuration can significantly expand the microscope's frequency capture range and is more sensitive to diffraction information from periodic linear structures, thus significantly improving imaging resolution and providing a new approach for high-resolution characterization of sample fine structures.

[0012] In summary, this invention utilizes a slight deflection of the objective lens's optical axis relative to the microscope's principal optical axis, combined with simple illumination path adjustment, to achieve super-resolution optical microscopy imaging. Compared to other super-resolution microscopy techniques, this method requires no complex and expensive hardware modifications to the microscope system; it only requires adjusting the objective lens deflection angle to within the 3-4° range. It is simple to operate, cost-effective, and can be directly implemented on conventional optical microscopes. Furthermore, the method proposed in this invention holds promise for compatibility with other super-resolution microscopy techniques, further pushing the resolution limits. Therefore, this invention has promising applications in areas such as fine material structure characterization and semiconductor device detection, and is expected to accelerate the visualization of nanoscale functional structures, driving technological progress in related fields.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] This invention provides a method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of a microscope, comprising the following steps:

[0015] The sample to be tested, which has a periodic linear array nanostructure on its surface, is placed on the rotating platform of the optical microscope stage.

[0016] Adjust the objective lens focal length to obtain a preliminary microscopic image of the surface of the sample to be tested;

[0017] Adjust the opening diameter of the adjustable aperture stop in the illumination system of the optical microscope to its minimum;

[0018] Rotate the objective lens turntable to create an angle of 3° to 4° between the objective lens optical axis and the microscope principal optical axis;

[0019] Fine-tuning the objective lens focal length allows the periodic linear array nanostructures on the surface of the sample to be clearly focused in the microscopic imaging field of view;

[0020] Rotate the rotating platform to adjust the orientation of the sample to be tested, so that the long axis of the periodic linear array nanostructure on its surface is parallel to the vertical direction in the microscopic imaging field of view, thereby achieving super-resolution optical microscopy imaging.

[0021] Preferably, the ratio of the line length to the line width of the linear array nanostructure is greater than 2.

[0022] Preferably, the line width of the linear array nanostructure is ≥80nm, the line length is ≥200nm, and the spacing between two adjacent linear array nanostructures is ≥80nm.

[0023] Preferably, the objective lens turret rotates in either clockwise or counterclockwise.

[0024] Preferably, the numerical aperture of the objective lens is not less than 0.8.

[0025] Preferably, the minimum opening diameter of the adjustable aperture stop is 1 to 1.1 mm.

[0026] The method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of the microscope, as described in this invention, has the following technical advantages compared to existing technologies:

[0027] 1. This invention ingeniously utilizes the optical path change caused by the slight deviation of the objective lens's optical axis from the microscope's principal optical axis. Combined with reducing the illumination aperture to improve illumination conditions, it achieves super-resolution imaging on a conventional optical microscope without requiring complex hardware modifications to the microscope system. This method is simple to operate, retains the real-time dynamic observation characteristics of optical microscopes, and improves the microscope's imaging resolution from the diffraction-limited approximately 300 nm to the 100 nm level, meeting the requirements for fine characterization of periodic nanostructures on the surface of samples such as semiconductor chips. This invention is expected to find applications in materials characterization, integrated circuit testing, and other fields, possessing significant technical value and application prospects.

[0028] 2. The method of this invention is simple to operate and easy to promote. This invention can achieve super-resolution imaging using a conventional optical microscope, requiring only simple adjustments to the objective lens turret and illumination system, without the need for complex and expensive modifications to the microscope hardware. Therefore, this invention has a low technical threshold and low cost, making it easy to promote and apply in various laboratories and industrial settings, and has good practicality.

[0029] 3. The method of this invention provides real-time dynamic imaging with a large field of view. Unlike super-resolution fluorescence microscopy and other techniques, this method eliminates the need for cumbersome pretreatment such as fluorescent labeling of samples, and avoids point-by-point scanning imaging like near-field scanning optical microscopy, significantly reducing sample preparation and image acquisition time. Using this invention, samples can be observed in real-time, dynamically, and non-destructively. Furthermore, while breaking the diffraction limit, this invention retains approximately half the field of view imaging capability of conventional microscopes, facilitating the analysis of macroscopic morphology and overall structure of samples.

[0030] 4. The method of this invention significantly improves imaging resolution: For samples with periodically arranged linear nanostructures, such as the surface of integrated circuit chips, this invention, by optimizing the objective lens deflection angle and illumination conditions, can improve the spatial resolution of the microscope by 2 times, from the diffraction limit of approximately 300 nm to the order of 100 nm. Using this invention, fine structural details that are difficult to distinguish with conventional microscopes can be clearly observed, providing a powerful tool for fine characterization and failure analysis in related fields.

[0031] 5. The method of this invention has broad application prospects; it has promising applications in multiple fields. In the semiconductor industry, it can be used for non-destructive testing and failure analysis of nanopatterns on chip surfaces, helping to improve chip manufacturing yield and reliability. In materials science, it can realize in-situ characterization and dynamic observation of nanomaterials, providing intuitive evidence for the research, optimization, and application of new materials. Furthermore, the combination of this invention with other super-resolution microscopy techniques is expected to further break through resolution bottlenecks, meeting the increasingly sophisticated characterization requirements of related fields, and possesses great development potential. Attached Figure Description

[0032] 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 these drawings without creative effort.

[0033] Figure 1 The photograph shows the actual object when the objective lens turret is rotated 4 mm clockwise, causing the objective lens optical axis to deviate from the principal optical axis of the microscope by 3.6°. It demonstrates the key structure for adjusting the objective lens deflection angle in this invention.

[0034] Figure 2 These are standard photographs taken when the optical axis of the objective lens coincides with the principal optical axis of the microscope (0°).

[0035] Figure 3To achieve super-resolution microscopy imaging of the periodic linear array nanostructures on the surface of a Blu-ray disc when the optical axis of the 100x objective lens is deviated from the principal optical axis by 3.6° and the aperture stop opening diameter is adjusted to the minimum, using the method of the present invention;

[0036] Figure 4 for Figure 3 The magnified view clearly shows the super-resolution imaging effect achieved by the method of the present invention on a 100nm pitch linear array structure;

[0037] Figure 5 Microscopic imaging of the Blu-ray disc surface linear array structure at a 30° angle to the vertical direction of the field of view, with the optical axis of the 100x objective lens deviating from the principal optical axis by 3.6° and the aperture stop opening diameter adjusted to the minimum.

[0038] Figure 6 for Figure 5 A magnified view of a portion of the image;

[0039] Figure 7 Microscopic imaging of the Blu-ray disc surface linear array structure at a 60° angle to the vertical direction of the field of view, with the optical axis of the 100x objective lens deviating from the principal optical axis by 3.6° and the aperture stop opening diameter adjusted to the minimum.

[0040] Figure 8 for Figure 7 A magnified view of a portion of the image;

[0041] Figure 9 Microscopic imaging of the Blu-ray disc surface linear array structure when the optical axis of the 100x objective lens is deviated from the principal optical axis by 3.6° and the aperture stop opening diameter is adjusted to the minimum;

[0042] Figure 10 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens offset from the principal optical axis by 3.6° and the aperture stop diameter adjusted to the maximum.

[0043] Figure 11 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens coinciding with the principal optical axis (0°) and the aperture stop diameter adjusted to the minimum.

[0044] Figure 12 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blue Light Disk under the conditions that the optical axis of the 100x objective lens coincides with the principal optical axis (0°) and the microscope is used in dark field imaging mode.

[0045] Figure 13 High-resolution atomic force microscopy (AFM) image of the periodic linear array nanostructures on the surface of a Blu-ray disc;

[0046] Figure 14 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens deviating 1° from the principal optical axis and the aperture stop diameter adjusted to the minimum.

[0047] Figure 15 for Figure 14 A magnified view of a portion of the image;

[0048] Figure 16 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens offset from the principal optical axis by 2° and the aperture stop diameter adjusted to the minimum.

[0049] Figure 17 for Figure 16 A magnified view of a portion of the image;

[0050] Figure 18 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens offset from the principal optical axis by 3° and the aperture stop diameter adjusted to the minimum.

[0051] Figure 19 for Figure 18 A magnified view of a portion of the image;

[0052] Figure 20 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens offset from the principal optical axis by 4° and the aperture stop diameter adjusted to the minimum.

[0053] Figure 21 for Figure 20 A magnified view of a portion of the image;

[0054] Figure 22 Microscopic imaging of a vertically arranged linear array structure on the surface of a Blu-ray disc, with the optical axis of the 100x objective lens offset from the principal optical axis by 4.5° and the aperture stop diameter adjusted to the minimum.

[0055] Figure 23 Microscopic imaging of a vertically arranged linear array structure on the surface of a semiconductor chip under the conditions that the optical axis of the 100x objective lens is deviated from the principal optical axis by 3° and the aperture stop opening diameter is adjusted to the minimum.

[0056] Figure 24 for Figure 23 A magnified view of a portion of the image;

[0057] Figure 25 Microscopic imaging of a vertically arranged linear array structure on the surface of a semiconductor chip, with the optical axis of the 100x objective lens coinciding with the principal optical axis (0°) and the aperture stop diameter adjusted to the minimum.

[0058] Figure 26 for Figure 25A magnified view of a portion of the image. Detailed Implementation

[0059] The present invention will be further illustrated below with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of the invention.

[0060] The method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of the microscope, according to the present invention, includes the following steps:

[0061] S1. Place the sample to be tested, which has a periodic linear array nanostructure on its surface, on the rotating platform of the optical microscope stage.

[0062] S2. Adjust the objective lens focal length to obtain a preliminary microscopic image of the surface of the sample to be tested;

[0063] S3. Adjust the opening diameter of the adjustable aperture stop in the illumination system of the optical microscope to its minimum.

[0064] S4. Rotate the objective lens turntable to create an angle of 3° to 4° between the objective lens optical axis and the microscope principal optical axis.

[0065] S5. Fine-tune the objective lens focal length to clearly focus the periodic linear array nanostructure on the surface of the sample under test in the microscopic imaging field of view.

[0066] S6. Rotate the rotating platform to adjust the orientation of the sample to be tested so that the long axis of the periodic linear array nanostructure on its surface is parallel to the vertical direction in the microscopic imaging field of view, thereby achieving super-resolution optical microscopic imaging.

[0067] In some embodiments, the numerical aperture of the objective lens is not less than 0.8. Specifically, the numerical aperture (NA) of an optical system is a dimensionless number used to measure the angular range of light that the system can collect. The numerical aperture of the objective lens determines its resolution. The larger the numerical aperture, the stronger the light-gathering ability of the objective lens and the higher its resolution.

[0068] In some embodiments, the aperture stop slider in the microscope optical path is moved to the position of minimum aperture opening diameter. The specific value of the minimum aperture opening diameter depends on the microscope model. The aperture opening diameter adjustment range of a conventional microscope is usually about 1 mm to 9 mm, that is, the minimum aperture opening diameter is about 1 to 1.1 mm.

[0069] In some embodiments, a method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of the microscope includes the following steps:

[0070] S1. An optical microscope is provided, equipped with an objective lens, objective turret, stage, 360° rotating platform, illumination system, adjustable aperture diaphragm, and image acquisition camera. The 360° rotating platform can rotate within 0 to 360° and is located on the stage. The sample to be observed is located on the 360° rotating platform. Figure 1 As shown, adjust the objective lens focal length to obtain a preliminary microscopic image of the sample surface;

[0071] S2. Adjust the opening diameter of the adjustable aperture stop in the lighting system to the minimum to optimize the uniformity of the lighting beam and image contrast.

[0072] S3. Rotate the objective lens turret so that the optical axis of the objective lens deviates from the principal optical axis of the microscope by 3° to 4° (a scale is attached to the objective lens turret and the turret support to precisely control the objective lens deflection angle), and use the angle adjustment and fixing mechanism of the objective lens turret to keep this deviation angle constant; the objective lens turret can be rotated clockwise or counterclockwise. When rotating clockwise, the super-resolution image appears in the right half of the field of view, and when rotating counterclockwise, the super-resolution image appears in the left half of the field of view;

[0073] S4. Under the conditions of steps S2 and S3, fine-tune the objective lens focal length to make the nanostructure of the sample surface clearly imaged in the field of view.

[0074] S5. Rotate the platform 360° to adjust the sample orientation so that the long axis of its surface linear nanostructures is parallel to the vertical direction in the field of view, thereby obtaining the optimal super-resolution imaging effect. Under the above conditions, the imaging resolution of this method can reach the 100nm level.

[0075] In some embodiments, the surface of the sample to be tested in this invention has a periodic linear array nanostructure. Specifically, the periodic linear array nanostructure is a plurality of parallel and spaced protrusions or grooves. The ratio of the line length to the line width of the linear array nanostructure is greater than 2. The line width of the linear array nanostructure is ≥80nm, the line length is ≥200nm, and the spacing between two adjacent linear array nanostructures is ≥80nm. That is, the width of the protrusion or groove is ≥80nm, the length is ≥200nm, and the spacing between two adjacent protrusions or the spacing between two adjacent grooves is ≥80nm.

[0076] The following specific embodiments further illustrate the method for achieving super-resolution optical microscopy imaging based on the objective lens optical axis deviating from the principal optical axis of the microscope. This section further describes the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0077] The following examples are all bright-field imaging.

[0078] Example 1

[0079] This embodiment proposes a method for achieving super-resolution optical microscopy imaging based on the objective lens optical axis deviating from the microscope principal optical axis. The specific process is as follows:

[0080] (1) Sample preparation:

[0081] Blu-ray discs with periodic linear nanoarray structures on their surfaces were selected as the observation samples, with a periodic spacing of 100 nm. That is, the linear nanoarray structure on the surface of the Blu-ray disc consists of multiple parallel grooves and protrusions, with a protrusion formed between two adjacent grooves. The width of the groove is 100 nm, the width of the protrusion is 200 nm, and the area between two adjacent protrusions is a groove. The spacing between two adjacent protrusions is the width of the groove, 100 nm.

[0082] (2) Adjustment of optical microscope:

[0083] A Nikon LV100 reflective illumination optical microscope was used, equipped with a 100x objective lens (Nikon LU Plan 100×, numerical aperture 0.9), objective turret, sample stage, 360° rotating platform, halogen lamp illumination source, adjustable aperture diaphragm, and 4K high-resolution camera. The 360° rotating platform was placed on the sample stage, and the Blu-ray disc sample was placed in the center of the rotating platform. The objective lens focal length was adjusted to obtain a clear image of the sample surface. At this point, the optical axis of the objective lens coincided with the principal optical axis of the microscope, i.e., the angle between them was 0°.

[0084] (3) Super-resolution optical microscopy:

[0085] Move the aperture stop lever in the microscope's optical path to the position with the smallest aperture opening diameter, which is approximately 1 mm. Slightly rotate the objective lens turret to deflect the objective lens's optical axis 3.6° relative to the microscope's principal optical axis (clockwise, i.e., the objective lens's optical axis forms a 3.6° angle with the microscope's principal optical axis), and simultaneously fine-tune the objective lens's focal length to refocus on the sample surface. At this point, the brightness of the left half of the microscopic imaging field of view decreases, while the right half presents a clear imaging area. Rotate the 360° rotating platform to adjust the sample's orientation so that the long axis of its surface linear nanoarrays is parallel to the vertical direction of the imaging field of view.

[0086] Figure 1A photograph shows the actual photograph of the objective lens being rotated 4 mm clockwise to deflect its optical axis off the microscope's principal optical axis. Scales are attached to both the objective lens turret and its support for precise control of the objective lens deflection angle. The objective lens turret has a diameter of 40 mm, and a 4 mm rotation corresponds to a deflection angle of 3.6°. The 360° rotating platform on the stage is used to adjust the orientation of the linear nanoarray in the sample within the imaging field of view.

[0087] Figure 2 This is a standard imaging photograph taken when the objective lens optical axis is coaxial with the microscope principal optical axis (deflection angle 0°), at which point the 0 mark on the objective lens turret and the support coincide.

[0088] Figure 3 This image presents a super-resolution micrograph of the Blue Light disk surface obtained with an objective lens offset of 3.6° (i.e., an angle of 3.6° between the objective lens optical axis and the microscope principal optical axis) and the aperture stop at its minimum setting. The linear array is parallel to the vertical direction of the field of view. A linear nanoarray structure with a period of 100 nm can be clearly distinguished from the right half of the image.

[0089] Figure 4 for Figure 3 The magnified image clearly demonstrates the super-resolution imaging effect of this method on the periodic linear array on the surface of a Blu-ray disc. The bright bars in the image correspond to the raised portions of the nanoarray, with a width of 200 nm; the dark areas between adjacent bright bars correspond to the groove portions of the nanoarray, with a width of 100 nm.

[0090] Figure 5 This demonstrates a microscopic image obtained by adjusting the sample orientation using a 360° rotating platform, while maintaining a 100x objective lens with a 3.6° off-axis and a minimal aperture opening. The angle between the linear nanoarray direction and the vertical direction of the imaging field of view was 30°. It can be seen that the imaging resolution in the right half of the imaging field of view decreased in this configuration.

[0091] Figure 6 yes Figure 5 The magnified image further verifies that even when the linear nanoarray is deviated from the vertical direction of the field of view by 30°, although the array structure with a period of about 100 nm can still be distinguished, the imaging resolution is significantly lower than before. Figure 4 It has decreased somewhat.

[0092] Figure 7 This demonstrates a super-resolution micrograph when the orientation of the linear nanoarray is further adjusted to form a 60° angle with the vertical direction of the field of view, while maintaining a 100x objective lens with an off-axis of 3.6° and a minimum aperture. At this point, the linear nanoarray structure on the surface of the Blu-ray disc is almost indistinguishable from the right half of the image.

[0093] Figure 8 yes Figure 7The magnified view further confirms that when the angle between the direction of the linear nanoarray and the vertical direction of the field of view reaches 60°, the super-resolution imaging capability further decreases, and the fine structure of the nanoarray cannot be clearly distinguished.

[0094] Figure 9 This demonstrates a microscopic image obtained when the angle between the direction of the linear nanoarray and the vertical direction of the field of view is further increased to 90°, while maintaining a 100x objective lens with an off-axis of 3.6° and a minimum aperture. At this point, the linear nanostructures on the Blu-ray disc surface are also indistinguishable from the right half of the image.

[0095] Figure 10 This demonstrates a microscopic image of a Blue Light disk surface obtained with the objective lens off-axis at 3.6° but the aperture diaphragm opening at its maximum (i.e., the diaphragm stop lever in the microscope's optical path is moved to the position of the maximum aperture opening diameter, approximately 9 mm). The image shows a linear nanoarray oriented parallel to the vertical direction of the field of view. Under these illumination conditions, the 100 nm feature linear nanostructures are indistinguishable.

[0096] Figure 11 This study presents a microscopic image of a Blue Light disk surface obtained using the microscope's standard bright-field imaging mode, with the objective optical axis coaxial with the microscope's principal optical axis (offset angle of 0°) and the aperture stop at its minimum. The linear nanoarray is oriented parallel to the vertical direction of the field of view. According to the Abbe diffraction limit formula: d = 0.5λ / NA, where d is the minimum resolvable distance, λ is the illumination wavelength, and NA is the numerical aperture of the objective lens. For white light illumination (assuming an average wavelength of 550 nm) and an objective lens with a numerical aperture of 0.9, the diffraction-limited resolution of the microscope is approximately 306 nm. Therefore, in standard bright-field imaging mode, the 100 nm-scale linear nanostructures are much smaller than the diffraction-limited resolvable distance and cannot be clearly resolved.

[0097] Figure 12 Showing in with Figure 11 Microscopic images of the Blue Light Disc surface obtained using the microscope's conventional dark-field imaging mode under the same coaxial objective conditions. (Comparison) Figure 11 It can be seen that although dark field illumination can enhance the imaging contrast to some extent, it still cannot achieve clear resolution of 100nm-scale linear nanoarrays.

[0098] Figure 13 The image shows the surface morphology of the Blu-ray disc obtained using atomic force microscopy (AFM). As a morphology reference, it clearly shows the fine structure of the periodic linear nanoarray on the surface of the Blu-ray disc at the nanoscale, confirming that the groove width between adjacent protrusions is 100 nm.

[0099] In summary, the experimental results of this embodiment demonstrate that, under optimized optical path conditions with an objective lens off-axis of 3.6° and a minimum aperture diaphragm opening, conventional optical microscopy can achieve super-resolution imaging of fine structures at the 100 nm scale when the major axis of the linear nanostructures on the sample surface (such as the nanoarrays on the surface of a Blu-ray disc) is parallel to the vertical direction of the imaging field of view. However, when the nanoarray direction deviates significantly from the vertical direction, the aperture diaphragm opening is too large, or conventional coaxial bright-field / dark-field illumination is used, it is difficult to overcome the optical diffraction limit and achieve super-resolution imaging. This method, utilizing a conventional microscope combined with a unique off-axis illumination optical path, provides a novel, simple, and low-cost technical approach for the super-resolution characterization of nanowire structures.

[0100] Example 2

[0101] This embodiment provides a method for achieving super-resolution optical microscopy imaging based on the objective optical axis deviating from the microscope principal optical axis. This method is essentially the same as Embodiment 1, with the main difference being that the deflection angle of the objective optical axis relative to the microscope principal optical axis is different in step (3) of this embodiment. This embodiment systematically evaluated the impact of objective deflection angles of 1°, 2°, 3°, 4°, and 4.5° (i.e., the objective optical axis relative to the microscope principal optical axis produces angles of 1°, 2°, 3°, 4°, and 4.5°) on the super-resolution imaging quality, in order to optimize the deflection angle.

[0102] Figure 14 This image shows a microscopic image of the Blu-ray disc surface obtained with an objective lens off-axis of 1° and the aperture stop adjusted to its minimum, in which the linear nanoarray is oriented parallel to the vertical direction of the field of view. At this off-axis angle, the linear nanoarray structure on the Blu-ray disc surface cannot be clearly distinguished throughout the entire imaging field of view.

[0103] Figure 15 yes Figure 14 The magnified image further confirms that super-resolution imaging of the linear nanoarray on the Blu-ray disc surface cannot be achieved at an off-axis angle of 1°.

[0104] Figure 16 This displays a microscopic image of the Blu-ray disc surface obtained with an objective lens offset of 2° and the aperture stop adjusted to its minimum. (Compared to...) Figure 14 In contrast, the right half of the imaging field of view now begins to show the undulating contours of a linear nanoarray.

[0105] Figure 17 yes Figure 16 The magnified view shows that the super-resolution imaging quality is improved at a 2° off-axis angle, but it is still insufficient to fully resolve the fine structural features of the linear nanoarray.

[0106] Figure 18This image shows a microscopic image of the Blu-ray disc surface obtained with the objective lens off-axis at 3° and the aperture stop adjusted to its minimum. It can be seen that the right half of the imaging field of view at this point clearly reveals a linear nanoarray structure with a period of 100 nm.

[0107] Figure 19 yes Figure 18 The magnified view further demonstrates that conventional optical microscopy achieved super-resolution imaging of a 100nm feature-scale linear nanoarray on the surface of the Blu-ray Disc at a 3° off-axis angle.

[0108] Figure 20 This displays a microscopic image of the Blu-ray disc surface obtained with an objective lens off-axis of 4° and the aperture stop adjusted to its minimum. Figure 18 In comparison, the area of ​​super-resolution imaging in the imaging field of view is reduced, but the linear nanoarray with a period of about 100 nm can still be clearly distinguished in the bright area of ​​the right half.

[0109] Figure 21 yes Figure 20 The magnified image confirms that the super-resolution imaging quality remains high even at a 4° off-axis angle, clearly distinguishing the fine linear nanoarray structure on the Blu-ray disc surface.

[0110] Figure 22 This image shows a microscopic image of the Blu-ray disc surface obtained with the objective lens off-axis at 4.5° and the aperture stop at its minimum. It can be seen that the brightness of the entire imaging field is very low at this setting, making it impossible to obtain a clear super-resolution image.

[0111] In summary, this embodiment systematically evaluated the impact of different objective lens off-axis angles on super-resolution imaging quality. It found that within an off-axis angle range of 3° to 4°, conventional optical microscopes can achieve optimal super-resolution imaging of a 100nm linear nanoarray on the surface of a Blu-ray disc. However, when the off-axis angle is too small (e.g., 1° and 2°) or too large (e.g., 4.5°), ideal super-resolution imaging cannot be obtained. The results of this embodiment provide crucial experimental evidence and quantitative reference for optimizing objective lens off-axis angles.

[0112] Example 3

[0113] This embodiment provides a method for achieving super-resolution optical microscopy based on the objective optical axis deviating from the principal optical axis of a microscope. It is basically the same as that in Embodiment 1, the main difference being that a semiconductor chip with a periodic linear nanoarray structure is selected as the observed sample in step (1) of this embodiment. The length of the lines in the rectangular block pattern of the chip is 10 μm, the line width is 300 nm, and the spacing between two adjacent lines is 110 nm.

[0114] Figure 23This image shows a microscopic image of the chip surface obtained with the objective lens off-axis at 3° and the aperture stop adjusted to its minimum, in which the linear nanoarray is oriented parallel to the vertical direction of the field of view. It can be seen that the linear nanoarray structure on the chip surface is clearly distinguishable in the right half of the imaging field of view.

[0115] Figure 24 yes Figure 23 The magnified view further demonstrates the super-resolution imaging effect achieved by the method of the present invention on the periodic linear nanoarray on the chip surface, and its fine structural features can be clearly identified.

[0116] Figure 25 This image shows a microscopic image of the chip surface obtained when the objective lens and the microscope's principal optical axis are coaxial (off-axis angle of 0°) and the aperture stop is adjusted to its minimum. The linear nanoarray is parallel to the vertical direction of the field of view. It can be seen that under conventional coaxial illumination, the fine structure of the periodic linear nanoarray on the chip surface cannot be resolved in the entire imaging field of view.

[0117] Figure 26 yes Figure 25 The magnified images further confirm that, under conventional microscopy imaging conditions, super-resolution imaging of the linear nanoarrays on the chip surface is impossible due to the diffraction limit.

[0118] The results of this embodiment demonstrate that the super-resolution optical microscopy imaging method based on objective lens off-axis proposed in this invention is not only applicable to the characterization of optical storage media such as Blu-ray discs, but also to the fine structure of linear nanoarrays on the surface of semiconductor chips. This result further expands the application scope of this invention, indicating that this method has good application prospects in defect detection and failure analysis in semiconductor device manufacturing.

[0119] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of a microscope, characterized in that, Includes the following steps: The sample to be tested, which has a periodic linear array nanostructure on its surface, is placed on the rotating platform of the optical microscope stage. Adjust the objective lens focal length to obtain a preliminary microscopic image of the surface of the sample to be tested; Adjust the opening diameter of the adjustable aperture stop in the illumination system of the optical microscope to its minimum; Rotate the objective lens turntable to create an angle of 3° to 4° between the objective lens optical axis and the microscope principal optical axis; Fine-tuning the objective lens focal length allows the periodic linear array nanostructures on the surface of the sample to be clearly focused in the microscopic imaging field of view; Rotate the rotating platform and adjust the orientation of the sample to make the long axis of its periodic linear array nanostructure parallel to the vertical direction in the microscopic imaging field of view, thereby achieving super-resolution optical microscopy imaging. The line array nanostructure has a line width ≥ 80 nm, a line length ≥ 200 nm, and a spacing of ≥ 80 nm between two adjacent line array nanostructures. The numerical aperture of the objective lens is not less than 0.8; The minimum opening diameter of the adjustable aperture stop is 1 to 1.1 mm.

2. The method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of the microscope as described in claim 1, characterized in that, The ratio of the line length to the line width of the linear array nanostructure is greater than 2.

3. The method for achieving super-resolution optical microscopy based on the objective lens optical axis deviating from the principal optical axis of the microscope as described in claim 1, characterized in that, The objective lens turret can rotate clockwise or counterclockwise.

Images