Method for realizing super-resolution optical microscopic imaging based on deviation of optical axis of objective lens from primary optical axis of microscope

Abstract

The invention provides a method for realizing super-resolution optical microscopic imaging on the basis that an optical axis of an objective lens deviates from a primary optical axis of a microscope. The invention provides a method for realizing super-resolution imaging by using a conventional optical microscope without modifying or adding complex equipment. By finely adjusting the angle of the objective lens turntable, an included angle of 3-4 degrees is formed between the optical axis of the objective lens and the main optical axis of the microscope, and the opening diameter of the aperture diaphragm is reduced, so that the resolution of the microscope can be improved from about 300nm to 100nm. According to the method, the optical imaging condition of the microscope is reasonably optimized and utilized, and the method is particularly suitable for high-resolution, real-time and nondestructive observation of the periodic linear array nanostructure on the surface of the sample. The method is easy to operate and low in cost, the application range of a conventional optical microscope is expanded, and the method has good practical value and application prospects in the fields of material microstructure analysis, semiconductor chip detection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of optical microscopic imaging, and in particular to a method for realizing super-resolution optical microscopic imaging based on the deviation of an objective lens optical axis from a main optical axis of a microscope. Background Art

[0002] Optical microscopy is one of the most commonly used microscopic imaging tools and is widely used in materials science, biomedicine, semiconductors and other fields. However, due to the optical diffraction limit, the imaging resolution of conventional optical microscopes is usually limited to 200-300nm, which is difficult to meet the needs of high-resolution imaging and analysis of fine microstructures in samples. To overcome this limitation, researchers have developed a variety of super-resolution optical microscopy techniques, including super-resolution fluorescence microscopy, near-field super-resolution imaging technology 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), use the controllable excitation and emission of fluorescent molecules to achieve super-resolution imaging of biological samples, with an imaging resolution of up to 20nm. However, this type of technology relies on fluorescent labeling of samples, which is complex to operate, expensive, and has strict requirements on the experimental environment and the samples themselves, limiting its application in daily testing in the field of materials.

[0004] Near-field super-resolution imaging techniques, such as near-field scanning optical microscopes, microsphere super-lenses, and solid immersion lenses, introduce nanoscale optical elements on the sample surface to capture the evanescent waves in the near-field region to achieve super-resolution imaging of the sample, with an imaging resolution of 50-100nm. However, such techniques usually require complex experimental devices and delicate manipulation, with slow imaging speed or limited field of view, and are limited in high-throughput observation of large-area samples.

[0005] Structured illumination microscopy (SIM) projects periodic structured light onto the sample, and uses the modulation effect of optical stripes on the high-frequency information of the sample to achieve an approximately 2-fold improvement in the resolution of conventional microscopes, with imaging resolution of up to 100-120nm. However, SIM has high requirements on the stability and precision of the optical system, the equipment cost is relatively expensive, and obtaining super-resolution images requires more complex algorithm processing and image reconstruction.

[0006] In addition, dark-field microscopy and oblique illumination microscopy use special illumination methods to enhance the microscope's imaging capabilities for sample fine structures to a certain extent. Dark-field microscopy uses an annular aperture or dark-field condenser to produce a centrally shielded annular illumination light, which causes the light to be incident on the sample surface at a large inclination angle (usually 60-80°). The objective lens only collects scattered light from the sample surface and filters out background light, thereby better highlighting the sample's fine structure against a dark background. Oblique illumination microscopy introduces elements such as oblique baffles or eccentric apertures into the microscope's illumination light path, allowing the illumination light to illuminate the sample surface at a certain inclination angle (usually 5-45°), improving the image resolution to a certain extent. However, due to the optical diffraction limit, the imaging resolution of these two technologies is limited, and it is difficult to truly achieve super-resolution imaging.

[0007] In summary, existing super-resolution microscopy techniques often rely on complex and expensive equipment, sophisticated manipulation, and cumbersome sample preparation, which makes it difficult to meet the daily needs of the materials field for simple, fast, low-cost, and high-resolution detection of samples. Therefore, it is urgent to develop a new super-resolution optical microscopy technique that does not require complex modifications to the microscope system, is easy to operate, and is low-cost, so as to achieve efficient and real-time detection of the fine nanoscale structure of the sample and effectively meet the application needs of production practice. Summary of the invention

[0008] In view of the limitations of existing optical microscopy imaging technology in characterizing the nanostructure of sample surfaces, the present invention proposes a new super-resolution imaging method based on a conventional optical microscope. This method precisely adjusts the relative angle between the objective lens optical axis and the main optical axis of the microscope so that the two form a slight deviation within the range of 3-4°, optimizes the imaging optical path, breaks through the limitation of strict parallelism of the optical axes in the classical microscopy imaging system, effectively improves the imaging resolution without introducing complex hardware, and realizes clear imaging of the nanoscale fine structure of the sample surface.

[0009] The super-resolution optical microscopy imaging method of the present invention is particularly suitable for the case where there are a large number of periodically arranged linear nanostructures on the sample surface, such as gate structures and photoresist patterns on the surface of semiconductor chips. When the optical axis of the objective lens deviates from the main optical axis of the microscope by 3 to 4 degrees, and the long axis of the periodic linear array structure is parallel to the vertical direction in the microscopic imaging field of view, the imaging resolution can be optimally improved. Under the appropriate deflection angle and a small aperture diaphragm opening diameter, the method of the present invention can increase the resolution of a conventional microscope from about 300nm to 100nm, achieving a 2-fold resolution gain.

[0010] In conventional optical microscopes, the objective optical axis is usually strictly parallel or coaxial with the main optical axis of the microscope and the normal of the sample surface. Although this optical path configuration is conducive to obtaining clear images, it is difficult to achieve super-resolution imaging due to the constraints of the diffraction limit. New oblique illumination microscopy technologies developed in recent years, such as inclined plane illumination microscopy and light sheet illumination microscopy, have improved imaging performance to a certain extent through special illumination methods, but their objective optical axis remains parallel to the main optical axis of the microscope, failing to break through the inherent limitations of the conventional microscope optical path.

[0011] Different from the existing oblique illumination technology, the present invention cleverly adjusts the angle of the objective lens optical axis relative to the main optical axis of the microscope, achieving non-collinearity of the optical axis within a small deflection range of 3 to 4 degrees, breaking the constraints of the traditional microscopic imaging optical path design. This novel optical axis deflection configuration can greatly expand the frequency capture range of the microscope, and is more sensitive to the diffraction information of periodic linear structures, thereby significantly improving the imaging resolution and providing a new way to characterize the fine structure of samples with high resolution.

[0012] In summary, the present invention utilizes a slight deflection of the objective lens optical axis relative to the main optical axis of the microscope, combined with simple illumination light path control, to achieve super-resolution optical microscopy imaging. Compared with other super-resolution microscopy techniques, this method does not require complex and expensive hardware modifications to the microscope system. It only requires adjusting the deflection angle of the objective lens to within the range of 3-4°. It is easy to operate, cost-effective, and can be directly implemented on a conventional optical microscope. In addition, the method proposed in the present invention is expected to be compatible with other super-resolution microscopy techniques to further break through the resolution limit. Therefore, the present invention has good application prospects in the fields of material fine structure characterization, semiconductor device detection, etc., and is expected to accelerate the visualization research process of nanoscale functional structures and promote technological progress in related fields.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] The present invention provides a method for realizing super-resolution optical microscopic imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope, comprising the following steps:

[0015] The sample to be tested having a periodic linear array nanostructure on its surface is placed on a rotating platform of an optical microscope stage;

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

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

[0018] Turn the objective turret so that the objective optical axis is at an angle of 3° to 4° relative to the main optical axis of the microscope;

[0019] Fine-tune the focal length of the objective lens so that the periodic linear array nanostructure on the surface of the sample to be measured can be clearly focused in the microscopic imaging field;

[0020] The rotating platform is rotated to adjust the orientation of the sample to be tested so that the long axis direction of the periodic linear array nanostructure on its surface is parallel to the vertical direction in the microscopic imaging field of view, thereby realizing super-resolution optical microscopic 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 ≥80 nm, the line length is ≥200 nm, and the spacing between two adjacent linear array nanostructures is ≥80 nm.

[0023] Preferably, the rotation direction of the objective lens turret includes 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 diaphragm is 1-1.1 mm.

[0026] Compared with the prior art, the method of the present invention for realizing super-resolution optical microscopic imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope has the following technical effects:

[0027] 1. The present invention cleverly utilizes the change in the optical path caused by the slight deviation of the objective lens optical axis from the main optical axis of the microscope, combined with the reduction of the illumination aperture diaphragm to improve the illumination conditions, to achieve super-resolution imaging on a conventional optical microscope without the need for complex hardware modifications to the microscope system. The method is easy to operate, retains the real-time dynamic observation characteristics of the optical microscope, and increases the imaging resolution of the microscope from the diffraction limit of about 300nm to the order of 100nm, meeting the needs of fine characterization of periodic nanostructures on the surface of samples such as semiconductor chips. The method of the present invention is expected to be applied in the fields of material characterization, integrated circuit detection, etc., and has significant technical value and application prospects;

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

[0029] 3. The method of the present invention has real-time dynamic imaging and a large field of view. Unlike technologies such as super-resolution fluorescence microscopy, the method of the present invention does not require tedious pre-processing of the sample such as fluorescent labeling, nor does it require point-by-point scanning imaging like near-field scanning optical microscopy, which greatly shortens the time for sample preparation and image acquisition. The present invention can be used to observe samples in real time, dynamically, and non-destructively. In addition, while breaking through the diffraction limit, the present invention can retain about half of the field of view imaging capability of a conventional microscope, making it easier to analyze the macroscopic morphology and overall structure of the sample.

[0030] 4. The imaging resolution of the method of the present invention is significantly improved: for samples with periodically arranged linear nanostructure features, such as the surface of integrated circuit chips, the present invention can increase the spatial resolution of the microscope by 2 times, from the diffraction limit of about 300nm to the order of 100nm, by optimizing the deflection angle of the objective lens and the lighting conditions. Using the present 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 the present invention has broad application prospects; the present invention has good application prospects in multiple fields. In the semiconductor industry, it can be used for nondestructive detection and failure analysis of nano-patterns on the surface of chips, which helps to improve the yield and reliability of chip manufacturing; in the field of materials science, it can realize the in-situ characterization and dynamic observation of nano-materials, providing an intuitive basis for the research and development, optimization and application of new materials. In addition, the combination of the present invention with other super-resolution microscopy technologies is expected to further break through the resolution bottleneck and meet the increasingly refined characterization requirements in related fields, which has great development potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 This is a real-life photograph of the objective lens turret rotating 4 mm clockwise, causing the objective lens optical axis to deviate by 3.6° from the main optical axis of the microscope, which demonstrates the key structure for adjusting the deflection angle of the objective lens in the present invention;

[0034] Figure 2 This is a conventional observation photo when the objective lens optical axis coincides with the microscope principal optical axis (0°);

[0035] Figure 3In order to adopt the method of the present invention, under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 3.6° and the aperture diaphragm opening diameter is adjusted to the minimum, the super-resolution microscopic imaging of the vertical arrangement of the periodic linear array nanostructures on the surface of the blue-ray disc is performed;

[0036] Figure 4 for Figure 3 The local enlarged image clearly shows the super-resolution imaging effect achieved by the method of the present invention on the 100nm spacing line array structure;

[0037] Figure 5 Under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 3.6° and the aperture diaphragm opening diameter is adjusted to the minimum, the microscopic imaging when the linear array structure on the surface of the Blu-ray disc is at an angle of 30° to the vertical direction of the field of view;

[0038] Figure 6 for Figure 5 A partial enlarged view of

[0039] Figure 7 Under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 3.6° and the aperture diaphragm opening diameter is adjusted to the minimum, the microscopic imaging when the linear array structure on the surface of the Blu-ray disc is at an angle of 60° to the vertical direction of the field of view;

[0040] Figure 8 for Figure 7 A partial enlarged view of

[0041] Fig. 9 Under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 3.6° and the aperture diaphragm opening diameter is adjusted to the minimum, the microscopic imaging when the linear array structure on the surface of the Blu-ray disc is at a 90° angle to the vertical direction of the field of view;

[0042] Fig.10 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 3.6° and the aperture diaphragm opening diameter is adjusted to the maximum;

[0043] Fig.11 Microscopic imaging of the 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 main optical axis (0°) and the aperture diaphragm opening adjusted to the minimum diameter;

[0044] Fig.12 Microscopic imaging of the 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 main optical axis (0°) and using the dark field imaging mode of the microscope;

[0045] Fig.13 This is a high-resolution atomic force microscope (AFM) microscopic image of the periodic linear array nanostructure on the surface of a Blu-ray disc;

[0046] Fig.14 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 1° and the aperture diaphragm opening diameter is adjusted to the minimum;

[0047] Fig.15 for Fig.14 A partial enlarged view of

[0048] Fig.16 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates 2° from the main optical axis and the aperture diaphragm opening diameter is adjusted to the minimum;

[0049] Fig.17 for Fig.16 A partial enlarged view of

[0050] Fig.18 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates 3° from the main optical axis and the aperture diaphragm opening diameter is adjusted to the minimum;

[0051] Fig.19 for Fig.18 A partial enlarged view of

[0052] Fig. 20 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates 4° from the main optical axis and the aperture diaphragm opening diameter is adjusted to the minimum;

[0053] Fig.21 for Fig. 20 A partial enlarged view of

[0054] Fig. 22 Microscopic imaging of the vertically arranged linear array structure on the surface of a Blu-ray disc under the condition that the optical axis of the 100x objective lens deviates from the main optical axis by 4.5° and the aperture diaphragm opening diameter is adjusted to the minimum;

[0055] Fig.23 Microscopic imaging of the vertical arrangement of linear array structures on the surface of a semiconductor chip under the condition that the optical axis of the 100x objective lens deviates 3° from the main optical axis and the aperture diaphragm opening diameter is adjusted to the minimum;

[0056] Fig.24 for Fig.23 A partial enlarged view of

[0057] Fig.25 Microscopic imaging of the vertical arrangement of linear array structures on the surface of a semiconductor chip under the condition that the optical axis of the 100x objective lens coincides with the main optical axis (0°) and the aperture diaphragm opening diameter is adjusted to the minimum;

[0058] Fig.26 for Fig.25A partial enlarged view of . DETAILED DESCRIPTION

[0059] The present invention will be further described below in conjunction with specific examples. However, it should be understood that these examples are only used to illustrate the present invention and do not constitute a limitation on the scope of the present invention.

[0060] The method of the present invention for realizing super-resolution optical microscopic imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope comprises the following steps:

[0061] S1. Place the sample to be tested having a periodic linear array nanostructure on the surface on a rotating platform of an optical microscope stage;

[0062] S2, adjusting the focal length of the objective lens 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 diaphragm in the illumination system of the optical microscope to the minimum

[0064] S4, rotate the objective turret so that the objective optical axis forms an angle of 3° to 4° with respect to the principal optical axis of the microscope;

[0065] S5, fine-tuning the focal length of the objective lens to make the periodic linear array nanostructure on the surface of the sample to be measured clearly focused in the microscopic imaging field;

[0066] S6. Rotate the rotating platform and adjust the orientation of the sample to be tested so that the long axis direction of the periodic linear array nanostructure on its surface is parallel to the vertical direction in the microscopic imaging field of view, thereby realizing 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 the resolution of the objective lens. 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 push rod on the microscope optical path is moved to the position of the 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 conventional microscopes is usually about 1mm to 9mm, that is, the minimum aperture opening diameter is about 1-1.1mm.

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

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

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

[0072] S3, rotating the objective turret so that the objective optical axis deviates by 3° to 4° relative to the principal optical axis of the microscope (a scale is attached to the objective turret and the turret bracket, respectively, for accurately controlling the deflection angle of the objective lens), and the angle adjustment and fixing mechanism of the objective turret is used to keep the deviation angle constant; the rotation direction of the objective turret can be clockwise or counterclockwise, and the super-resolution image appears in the right half of the field of view when rotating clockwise, and the super-resolution image appears in the left half of the field of view when rotating counterclockwise;

[0073] S4, under the conditions of steps S2 and S3, fine-tuning the focal length of the objective lens so that the nanostructure on the sample surface is clearly imaged in the field of view;

[0074] S5, rotating the 360° rotating platform, adjusting the sample orientation so that the long axis direction of the linear nanostructure on its surface is parallel to the vertical direction in the field of view, so as to obtain the best super-resolution imaging effect. Under the above conditions, the imaging resolution of this method can reach 100nm.

[0075] In some embodiments, the surface of the sample to be tested of the present 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 further describes the method for realizing super-resolution optical microscopic imaging based on the deviation of the optical axis of the objective lens from the main optical axis of the microscope with specific embodiments. 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. If not otherwise specified, the technical means adopted 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 embodiments are all bright field imaging.

[0078] Example 1

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

[0080] (1) Sample preparation:

[0081] A blue-ray disc with a periodic linear nanoarray structure on the surface was selected as an observation sample, wherein the periodic spacing of the linear array was 100nm; that is, the linear nanoarray structure on the surface of the blue-ray disc was composed of a plurality of parallel and spaced grooves and protrusions, a protrusion was formed between two adjacent grooves, the width of the groove was 100nm, the width of the protrusion was 200nm, the area between two adjacent protrusions was a groove, and the spacing between two adjacent protrusions was the width of the groove, 100nm;

[0082] (2)Optical microscope debugging:

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

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

[0085] Move the stop push rod of the diaphragm on the microscope optical path to the position of the minimum diaphragm opening diameter, at which point the diaphragm opening diameter is about 1 mm. Slightly rotate the objective turret to deflect the objective optical axis by 3.6° relative to the main optical axis of the microscope (clockwise, i.e., the objective optical axis produces an angle of 3.6° relative to the main optical axis of the microscope), and at the same time fine-tune the focal length of the objective to refocus on the sample surface. At this point, the brightness of the left half of the microscopic imaging field of view decreases, and the right half presents a clear imaging area. Turn the 360° rotating platform and adjust the sample orientation so that the long axis direction of the linear nanoarray on its surface is parallel to the vertical direction of the imaging field of view.

[0086] Figure 1The photo shows the actual object of rotating the objective turret 4mm clockwise to make the objective optical axis deviate from the main optical axis of the microscope. Scales are attached to the objective turret and the turret bracket respectively, which are used to accurately control the deflection angle of the objective lens. The diameter of the objective turret is 40mm, and the deflection angle corresponding to a rotation of 4mm is 3.6°. The 360° rotating platform on the stage is used to adjust the orientation of the linear nanoarray in the sample in the imaging field of view.

[0087] Figure 2 This is a normal imaging photograph when the objective optical axis is coaxial with the main optical axis of the microscope (deflection angle 0°), and the 0 scale on the objective turret and the bracket coincides.

[0088] Figure 3 The super-resolution microscopic image of the blue disc surface is shown when the objective lens is 3.6° off-axis (i.e., the objective lens optical axis forms an angle of 3.6° relative to the main optical axis of the microscope) and the aperture diaphragm is opened to the minimum, where the linear array direction is parallel to the vertical direction of the field of view. The linear nanoarray structure with a period of 100nm can be clearly distinguished from the right half of the image.

[0089] Figure 4 for Figure 3 The local enlarged image clearly shows the super-resolution imaging effect of the periodic line array on the surface of the Blu-ray disc using this method. The bright stripes in the image correspond to the raised part of the nanoarray, with a width of 200nm; the dark area between two adjacent bright stripes corresponds to the groove part of the nanoarray, with a width of 100nm.

[0090] Figure 5 The microscopic image is shown when the sample orientation is adjusted by a 360° rotating platform under the condition of keeping the 100x objective lens off-axis at 3.6° and the aperture diaphragm opening at the minimum, so that the angle between the linear nanoarray direction and the vertical direction of the imaging field of view is 30°. It can be seen that the imaging resolution of the right half of the imaging field of view is reduced at this time.

[0091] Figure 6 yes Figure 5 The local magnified image further verifies that when the linear nanoarray deviates from the vertical direction of the field of view by 30°, although the array structure with a period of about 100nm can still be distinguished, the imaging resolution is Figure 4 Has been reduced.

[0092] Figure 7 The super-resolution microscopic image is shown when the linear nanoarray is further adjusted to a 60° angle with the vertical direction of the field of view while maintaining the 100x objective lens off-axis at 3.6° and the aperture diaphragm at the minimum opening. At this point, the linear nanoarray structure on the surface of the Blu-ray disc is basically indistinguishable from the right half of the image.

[0093] Figure 8 yes Figure 7The local enlarged image further confirms that when the angle between the linear nanoarray direction 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] Fig. 9 The microscopic image is shown when the angle between the linear nanoarray and the vertical direction of the field of view is further increased to 90°, while maintaining the 100x objective lens at 3.6° off-axis and the aperture diaphragm at the minimum opening. At this time, the linear nanostructure on the surface of the Blu-ray disc cannot be distinguished from the right half of the image.

[0095] Fig.10 The image of the blue disc surface is shown when the objective lens is 3.6° off-axis but the aperture diaphragm is opened to the maximum, that is, the diaphragm stop push rod on the microscope optical path is moved to the position of the maximum diaphragm opening diameter, at which the diaphragm opening diameter is about 9mm. The direction of the linear nanoarray is parallel to the vertical direction of the field of view. Under this illumination condition, the linear nanostructure with a 100nm feature cannot be resolved.

[0096] Fig.11 The microscopic image of the surface of a blue-ray disc obtained using the conventional bright-field imaging mode of the microscope is shown under the conditions that the objective optical axis is coaxial with the main optical axis of the microscope (the off-axis angle is 0°) and the aperture diaphragm is opened to the minimum, where the direction of the linear nanoarray is 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 wavelength of the illumination light, and NA is the numerical aperture of the objective. For white light illumination (assuming an average wavelength of 550nm) and an objective with a numerical aperture of 0.9, the diffraction-limited resolution of the microscope is approximately 306nm. Therefore, in the conventional bright-field imaging mode, the 100nm-scale linear nanostructure cannot be clearly resolved because it is much smaller than the diffraction-limited resolution distance.

[0097] Fig.12 Demonstrated in Fig.11 Under the same objective lens coaxial conditions, a microscopic image of the blue-ray disc surface was obtained using the conventional dark field imaging mode of the microscope. Fig.11 It can be seen that although dark-field illumination can enhance the imaging contrast to a certain extent, it is still impossible to achieve clear resolution of 100nm scale linear nanoarrays.

[0098] Fig.13 This is a surface morphology image of a Blu-ray disc obtained using an atomic force microscope (AFM). As a morphology reference, it clearly shows the fine structure of the periodic linear nanoarray on the surface of the Blu-ray disc from the nanoscale, confirming that the width of the grooves between adjacent protrusion ridges is 100nm.

[0099] In summary, the experimental results of this embodiment show that under the optimized optical path conditions of 3.6° off-axis objective lens and minimum aperture diaphragm opening, when the long axis direction of the linear nanostructure on the sample surface (such as the nanoarray on the surface of a blue-ray disc) is parallel to the vertical direction of the imaging field of view, a conventional optical microscope can achieve super-resolution imaging of 100nm scale fine structures. However, when the direction of the nanoarray 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 break through the optical diffraction limit to achieve super-resolution imaging. This method uses a conventional microscope combined with a unique off-axis illumination optical path to provide a novel, simple and low-cost technical path for super-resolution characterization of nanowire structures.

[0100] Example 2

[0101] The present embodiment provides a method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope, which is basically the same as that of the first embodiment, except that the deflection angle of the objective lens optical axis relative to the main optical axis of the microscope in step (3) of the present embodiment is different. The present embodiment systematically evaluates the influence of the objective lens off-axis angles of 1°, 2°, 3°, 4° and 4.5° (i.e., the objective lens optical axis generates angles of 1°, 2°, 3°, 4° and 4.5° relative to the main optical axis of the microscope) on the quality of super-resolution imaging, so as to optimize the off-axis angle.

[0102] Fig.14 The microscopic image of the blue-ray disc surface is shown when the objective lens is 1° off-axis and the aperture diaphragm is opened to the minimum, in which the linear nanoarray direction is parallel to the vertical direction of the field of view. At this off-axis angle, the linear nanoarray structure on the surface of the blue-ray disc cannot be clearly distinguished in the entire imaging field of view.

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

[0104] Fig.16 Shows a microscopic image of the surface of a Blu-ray disc obtained with the objective lens 2° off-axis and the aperture diaphragm opened to the minimum. Fig.14 In contrast, the right half of the imaging field of view now begins to show the undulating contours of the linear nanoarray.

[0105] Fig.17 yes Fig.16 The local magnified image shows that at an off-axis angle of 2°, the super-resolution imaging quality is improved, but it is still not enough to fully resolve the fine structural features of the linear nanoarray.

[0106] Fig.18The microscopic image of the blue disc surface obtained when the objective lens is 3° off-axis and the aperture diaphragm is adjusted to the minimum opening is shown. It can be seen that at this time, the linear nanoarray structure with a period of 100nm can be clearly distinguished in the right half of the imaging field of view.

[0107] Fig.19 yes Fig.18 The enlarged local image further demonstrates that at an off-axis angle of 3°, a conventional optical microscope can achieve super-resolution imaging of the 100nm characteristic scale linear nanoarray on the surface of a Blu-ray disc.

[0108] Fig. 20 Shows a microscopic image of the surface of a Blu-ray disc obtained with the objective lens 4° off-axis and the aperture diaphragm opened to the minimum. Fig.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 100nm can still be clearly distinguished in the highlighted area in the right half.

[0109] Fig.21 yes Fig. 20 The local enlarged image confirms that at an off-axis angle of 4°, the super-resolution imaging quality is still high and can clearly distinguish the fine structure of the linear nanoarray on the surface of the Blu-ray disc.

[0110] Fig. 22 The microscopic image of the blue disc surface is shown when the objective lens is 4.5° off-axis and the aperture diaphragm is adjusted to the minimum opening. It can be seen that the brightness of the entire imaging field is very low at this time, and clear super-resolution imaging cannot be obtained.

[0111] In summary, this embodiment systematically evaluates the effect of different objective lens off-axis angles on the quality of super-resolution imaging, and finds that within the off-axis angle range of 3° to 4°, a conventional optical microscope can achieve the best super-resolution imaging effect for a 100nm linear nanoarray on the surface of a Blu-ray disc. When the off-axis angle is too small (such as 1° and 2°) or too large (such as 4.5°), ideal super-resolution imaging cannot be obtained. The results of this embodiment provide a key experimental basis and quantitative reference for optimizing the off-axis angle of the objective lens.

[0112] Example 3

[0113] The present embodiment provides a method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope, which is basically the same as that of the first embodiment, except that: in step (1) of the present embodiment, a semiconductor chip with a periodic linear nanoarray structure is selected as the observed sample. The length of the line in the rectangular square pattern of the chip is 10 μm, the width of the line is 300 nm, and the spacing between two adjacent lines is 110 nm.

[0114] Fig.23The microscopic image of the chip surface obtained when the objective lens is 3° off-axis and the aperture diaphragm is opened to the minimum is shown, in which the linear nanoarray direction is parallel to the vertical direction of the field of view. It can be seen that in the right half of the imaging field of view, the linear nanoarray structure on the chip surface is clearly resolved.

[0115] Fig.24 yes Fig.23 The local enlarged image 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] Fig.25 The microscopic image of the chip surface obtained when the objective lens is coaxial with the main optical axis of the microscope (the off-axis angle is 0°) and the aperture diaphragm is adjusted to the minimum opening, and the linear nanoarray direction 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 distinguished in the entire imaging field of view.

[0117] Fig.26 yes Fig.25 The local magnified image further confirms that under conventional microscope imaging conditions, due to the limitation of diffraction limit, it is impossible to achieve super-resolution imaging of linear nanoarrays on the chip surface.

[0118] The results of this example show that the super-resolution optical microscopy imaging method based on the objective lens deflection proposed by the present invention is not only applicable to the characterization of optical storage media such as blue-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 the present invention, indicating that the method has good application prospects in defect detection and failure analysis in semiconductor device manufacturing.

[0119] It can be understood that the technical features of the above-described embodiments can be arbitrarily combined. In order to make the description concise, not all possible combinations of the technical features in the above-described 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 only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. A method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope, characterized in that: The following steps are involved: The sample to be tested having a periodic linear array nanostructure on its surface is placed on a rotating platform of an optical microscope stage; Adjust the focal length of the objective lens to obtain a preliminary microscopic image of the surface of the sample to be tested; Adjust the opening diameter of the adjustable aperture diaphragm in the illumination system of the optical microscope to the minimum; Turn the objective turret so that the objective optical axis is at an angle of 3° to 4° relative to the main optical axis of the microscope; Fine-tune the focal length of the objective lens so that the periodic linear array nanostructure on the surface of the sample to be measured can be clearly focused in the microscopic imaging field; The rotating platform is turned to adjust the orientation of the sample to be tested so that the long axis direction 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.

2. The method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope according to claim 1, characterized in that: The ratio of the line length to the line width of the line array nanostructure is greater than 2.

3. The method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope according to claim 1, characterized in that: The line width of the line array nanostructure is ≥80nm, the line length is ≥200nm, and the distance between two adjacent line array nanostructures is ≥80nm.

4. The method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope according to claim 1, characterized in that: The rotation direction of the objective lens turret includes clockwise or counterclockwise.

5. The method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope according to claim 1, characterized in that: The numerical aperture of the objective lens is not less than 0.

8.

6. The method for realizing super-resolution optical microscopy imaging based on the deviation of the objective lens optical axis from the main optical axis of the microscope according to claim 1, characterized in that: The minimum opening diameter of the adjustable aperture diaphragm is 1-1.1 mm.

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