A method for manufacturing a sandwich microsphere type calibration board and a sandwich microsphere type calibration board

Abstract

The application provides a sandwich microsphere type calibration plate manufacturing method and a sandwich microsphere type calibration plate, and belongs to the field of optical detection calibration devices. The method provided by the application comprises the following steps: sequentially performing ultrasonic cleaning and plasma cleaning on a first glass substrate and a second glass substrate, and then blowing dry with nitrogen for standby; coating a microsphere dispersion liquid on one side surface of the first glass substrate, and then performing drying treatment to fix the granular medium microspheres on the one side surface of the first glass substrate; coating an optical adhesive on the one side surface of the first glass substrate on which the medium microspheres are fixed; aligning and adhering the second glass substrate to the first glass substrate coated with the optical adhesive, encapsulating the medium microspheres in a sandwich composed of the two glass substrates and the optical adhesive; and curing the optical adhesive. The manufacturing method and the sandwich microsphere type calibration plate provided by the application can solve the problems of easy falling of microspheres, insufficient subsurface depth and single particle size in the existing calibration plate.

Description

Technical Field

[0001] This application relates to the field of optical detection and calibration device technology, and in particular to a method for manufacturing a sandwich microsphere calibration plate and the sandwich microsphere calibration plate. Background Technology

[0002] Subsurface defects (SSDs) are one of the key factors affecting the performance and lifespan of optical components (such as precision optical glass and laser crystals). Among them, particulate defects mostly originate from tiny impurities or microbubbles left over from the material preparation process. Under laser irradiation, these defects are prone to causing light scattering, energy absorption, and local field enhancement, leading to a decrease in the imaging quality of the optical system and a significant reduction in the laser damage threshold (LIDT).

[0003] Currently, calibration board fabrication methods for simulating particulate SSDs include implanting dielectric microspheres inside or at the bottom of a wedge-shaped glass substrate, spin-coating a polymer film onto the substrate surface and embedding the microspheres, or directly encapsulating the microspheres with a thin-layer adhesive. Among these methods, implanting dielectric microspheres inside or at the bottom of a wedge-shaped glass substrate is prone to introducing microcracks or even substrate cracking during the implantation process (such as mechanical pressing or high-temperature treatment), resulting in a low yield. Furthermore, the adhesion between the implanted microspheres and the substrate material is weak, making them prone to loosening or even detachment during subsequent testing, cleaning, or long-term storage. This leads to unstable calibration signals or calibration board failure, failing to guarantee the long-term reliability and repeatability of the calibration work. Constructing SSDs using methods such as spin-coating polymer films onto a substrate surface and embedding microspheres, or directly encapsulating microspheres with a thin layer of adhesive, typically results in a very thin encapsulation layer, ranging from only a few hundred nanometers to 2 micrometers. The simulated particulate defects are located at the very shallow surface of the optical element, and their light scattering characteristics, signal intensity, and depth response cannot accurately characterize the optical behavior of deep particulate SSDs located tens of micrometers or even deeper below the surface in actual optical elements. Therefore, the system calibration results based on such shallow encapsulation calibration boards have limited applicability in practical applications.

[0004] In summary, both implantation and thin-film encapsulation solutions generally suffer from the difficulty of controlling the uniformity of microsphere distribution, and typically only provide microspheres of a single size on the same calibration plate. This cannot meet the requirements of detection systems in practical applications, which need to detect defects of different sizes and perform full-range calibration. Using multiple calibration plates of a single size is not only cumbersome to operate, but also introduces systematic errors. Therefore, there is an urgent need for a new calibration plate fabrication method that can simultaneously solve the problems of short calibration plate life due to easy microsphere detachment, insufficient subsurface depth preventing the simulation of deep defects, and the inability to meet multi-range calibration requirements due to the single particle size. Summary of the Invention

[0005] In view of this, this application provides a method for manufacturing a sandwich microsphere calibration plate and a sandwich microsphere calibration plate, which can solve the problems of easy microsphere detachment, insufficient subsurface depth and uniform particle size in existing calibration plates.

[0006] Specifically, this application is implemented through the following technical solution:

[0007] The first aspect of this application provides a method for manufacturing a sandwich microsphere calibration plate, the method comprising:

[0008] After cleaning the first glass substrate and the second glass substrate, they are dried with nitrogen gas for later use; wherein the thickness of the second glass substrate is less than the thickness of the first glass substrate, and the thickness of both the first glass substrate and the second glass substrate is less than 3 mm.

[0009] After coating a microsphere dispersion onto one side surface of the first glass substrate, the substrate is dried to fix the particulate media microspheres on one side surface of the first glass substrate.

[0010] An optical adhesive is coated on one side surface of the first glass substrate on which the dielectric microspheres are fixed;

[0011] The second glass substrate is aligned and bonded to the first glass substrate coated with the optical adhesive, and the dielectric microsphere is encapsulated in a sandwich composed of the two glass substrates and the optical adhesive.

[0012] The optical adhesive is cured.

[0013] A second aspect of this application provides a sandwich microsphere calibration plate, the calibration plate comprising:

[0014] First glass substrate;

[0015] A second glass substrate is disposed opposite to the first glass substrate, and the thickness of the second glass substrate is less than that of the first glass substrate;

[0016] Medium microspheres are disposed between the first glass substrate and the second glass substrate;

[0017] An optical adhesive layer is filled between the first glass substrate and the second glass substrate, and the dielectric microspheres are encapsulated and fixed therein to form a sandwich structure.

[0018] The sandwich microsphere calibration plate fabrication method and the sandwich microsphere calibration plate provided in this application solve the problems of easy microsphere detachment, insufficient subsurface depth, and uniform particle size in existing calibration plates by constructing a structure in which optical adhesive and dielectric microspheres are sandwiched between two glass substrates. First, this method completely seals the dielectric microspheres inside the sandwich layer, isolating them from the external environment, fundamentally overcoming the defects of easy microsphere detachment and wear in traditional solutions, ensuring signal stability and long lifespan of the calibration plate during long-term use. Second, by using a second glass substrate thinner than the lower substrate, a subsurface space with controllable depth is constructed together with the adhesive layer, allowing the encapsulated dielectric microspheres to realistically simulate particle defects with depths of tens to hundreds of micrometers in actual optical components, breaking through the limitation of shallow defect depth in traditional thin-film encapsulation solutions, and making the calibration results more practically meaningful. Finally, this sandwich structure serves as a universal platform, providing a technical basis for integrating microspheres of multiple particle sizes on the same calibration plate, thereby achieving single-plate coverage of multi-range calibration, greatly improving calibration efficiency and application scope. In practice, ultrasonic and plasma pretreatment ensured the ultra-cleanliness and high activity of the substrate, providing a foundation for the firm adhesion of the dielectric microspheres and the defect-free bonding of the interface. The process of first coating and drying the dielectric microspheres and then applying adhesive to bond them effectively avoided the aggregation and uneven distribution of the dielectric microspheres, ensuring the regularity of defect signals. The precise alignment and controllable curing process ensured that there were no air bubbles and low stress inside the interlayer, ultimately forming a package with excellent optical performance and a robust and durable structure. Attached Figure Description

[0019] Figure 1 Flowchart of Embodiment 1 of the method for fabricating the sandwich microsphere calibration plate provided in this application;

[0020] Figure 2 The image shows the test results of the calibration plate fabricated according to specific embodiment 1 as illustrated in this application;

[0021] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the sandwich microsphere calibration plate provided in this application;

[0022] Explanation of reference numerals in the attached figures:

[0023] 1: Second glass substrate;

[0024] 2: Optical adhesive layer;

[0025] 3: Medium microspheres;

[0026] 4: First glass substrate. Detailed Implementation

[0027] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0028] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used herein are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0029] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0030] The following specific embodiments are given to illustrate the technical solution of this application in detail.

[0031] Example 1

[0032] Figure 1 This is a flowchart of an embodiment of the method for fabricating the sandwich microsphere calibration plate provided in this application. Please refer to... Figure 1 The method provided in this embodiment may include:

[0033] S101. After cleaning the first glass substrate and the second glass substrate, dry them with nitrogen gas for later use; wherein the thickness of the second glass substrate is less than the thickness of the first glass substrate, and the thickness of both the first glass substrate and the second glass substrate is less than 3 mm.

[0034] It should be noted that the cleaning process includes, in sequence, ultrasonic cleaning and plasma cleaning.

[0035] The first and second glass substrates are the supporting materials for constructing the sandwich structure. The preferred materials are fused silica glass or K9 optical glass. Fused silica glass, due to its high transmittance and low coefficient of thermal expansion across the ultraviolet to infrared bands, is suitable for high-precision optical inspection applications; while K9 optical glass, with its lower cost, can meet most general inspection needs. The length and width dimensions of the two substrates are consistent, typically ranging from 20mm to 50mm, to accommodate the sample stages of common optical inspection systems.

[0036] In this design, the thickness of the first glass substrate is greater than that of the second glass substrate. Specifically, the first glass substrate, serving as the main support structure, has a thickness of 1mm to 3mm to balance mechanical strength and optical transmittance. The second glass substrate is thinner, ranging from 0.1mm to 0.3mm. This difference in thickness is designed to allow the second glass substrate, together with the subsequently coated optical adhesive layer, to create a subsurface space with controllable depth. This encapsulates the dielectric microspheres at a depth of tens to hundreds of micrometers below the surface of the optical element, more realistically simulating deep particulate defects in actual optical elements and effectively solving the problem of insufficient subsurface depth in traditional thin-film encapsulation solutions. Furthermore, the refractive index difference between the two substrates is controlled to ≤0.02, which minimizes stray light interference caused by interface reflection and ensures the accuracy of defect detection signals. Specifically, the difference in refractive index between the glass substrate and air will cause interfacial reflection. If the difference in refractive index between the two substrates is too large, double reflection will be formed at the interface between the first and second glass substrates and the optical adhesive, generating stray light that interferes with the defect detection signal. Controlling the difference to ≤0.02 can make the light transmit in the interlayer with almost no interfacial reflection, ensuring that the detection signal comes only from the medium microspheres.

[0037] To ensure the firm adhesion of the dielectric microspheres and the defect-free bonding of the interlayer interface in subsequent processes, the substrate needs to be pretreated. Specifically, firstly, ultrasonic cleaning with deionized water for 10-15 minutes at an ultrasonic power of 200-300W is performed to remove surface dust, oil, and other particulate contaminants. Subsequently, plasma cleaning is performed in an oxygen atmosphere for 5-8 minutes at a power of 80-120W to further remove organic residues and activate the substrate surface, enhancing its adhesion to the dielectric microspheres and optical adhesive. Finally, high-pressure nitrogen is used for drying to avoid water stains and ensure that the substrate is clean and dry before proceeding to the next process.

[0038] S102. After coating a microsphere dispersion onto one side surface of the first glass substrate, a drying process is performed to fix the particulate medium microspheres on one side surface of the first glass substrate.

[0039] First, a microsphere dispersion for coating needs to be prepared. Specifically, the selected medium microspheres are dispersed in a mixed solvent. The medium microspheres can be silica microspheres, polystyrene microspheres, or polymer microspheres. Among them, silica microspheres are suitable for high-precision calibration due to their excellent light transmittance and chemical stability; while polystyrene microspheres have a wide range of particle size selection and are cost-effective, making them suitable for general applications. To simulate defects of different sizes in real optical components, the particle size range of the medium microspheres is controlled between 100 nm and 10 μm, and the particle size deviation is required to be ≤5% to ensure the consistency of the calibration signal. In addition, at least three different particle sizes of medium microspheres can be fixed on the same calibration plate, so that a single calibration plate can cover multiple measurement ranges from microscopic to macroscopic detection, expanding its application range.

[0040] The mixed solvent consists of anhydrous ethanol and propylene glycol methyl ether acetate (PMA) in a volume ratio of 1:1 to 3:1. Anhydrous ethanol is highly volatile, quickly removing some solvent to prevent microsphere aggregation. Propylene glycol methyl ether acetate has moderate volatility, slowing down solvent evaporation and preventing the formation of a coffee ring effect (microspheres concentrating at the substrate edge) due to edge-drying followed by center-drying. This mixing ratio balances the requirements for rapid drying and uniform distribution. Therefore, this mixed solvent utilizes both the rapid volatility of ethanol and the moderate slow-drying properties of PMA to jointly prevent microsphere aggregation and the coffee ring effect before drying. Specifically, the concentration of the media microspheres in the mixed solvent is controlled between 0.1 and 1 wt%, within which a suitable surface distribution density can be obtained. During the preparation process, the mixed liquid needs to be ultrasonically treated for 10 to 20 minutes with an ultrasonic power of 100 to 200W to provide sufficient energy to break the van der Waals forces between the medium microspheres, ensuring that they are fully and uniformly dispersed in the mixed solvent and avoiding agglomeration that could affect the accuracy of the calibration plate.

[0041] Subsequently, the prepared microsphere dispersion is coated onto one side of the pretreated first glass substrate. The coating method can be either spin coating or spray coating, depending on the requirements. For spin coating, a spin coater is used to rotate the substrate at 1500 to 2500 rpm for 10 to 20 seconds, utilizing centrifugal force to evenly spread the dispersion, thus achieving a high-density, uniform distribution of the microspheres. For spray coating, a sprayer is used at a pressure of 0.1 to 0.3 MPa, a spraying distance of 5 to 10 cm, and a spray rate of 0.5 to 1 mL / min. This method is more suitable for uniform coating of large-area substrates and allows for better control of the distribution density of the microspheres.

[0042] After coating, the first glass substrate is placed on a heating table or oven at 60 to 80°C for drying for 10 to 20 minutes to allow the mixed solvent to evaporate completely. This allows the dielectric microspheres to adhere firmly to the substrate surface under the influence of van der Waals forces, forming a stable monolayer or sub-monolayer distribution. The drying process effectively prevents displacement of the dielectric microspheres during subsequent coating of optical adhesives and alignment, ensuring fixed microsphere positions and reliable calibration results.

[0043] S103. Coat one side surface of the first glass substrate on which the medium microspheres are fixed with an optical adhesive.

[0044] It should be noted that by applying an optical adhesive, the fixed dielectric microspheres can be initially encapsulated and wetted, preparing them for subsequent encapsulation and bonding with the second glass substrate. The optical adhesive serves three functions here: first, as an encapsulation medium, it completely encapsulates and fixes the dielectric microspheres within the sandwich structure; second, as an optical coupling medium, its refractive index must precisely match that of the upper and lower glass substrates to minimize interface reflection; and third, as a component of the subsurface space, it works with the second glass substrate to determine the burial depth of defects.

[0045] In practice, the selected optical adhesive should be a UV-curable or thermosetting optical adhesive with a refractive index controlled within the range of 1.45 to 1.55, and the refractive index difference between it and the first and second glass substrates should not exceed 0.03. This refractive index matching requirement ensures that when light passes through the multi-layer interface of glass-adhesive-glass, it will not generate extra stray light such as reflection and scattering due to refractive index mismatch, thereby avoiding interference from these non-defect signals on the scattered signals of the dielectric microspheres themselves, and ensuring the accuracy and signal-to-noise ratio of the calibration results.

[0046] It is important to note that the coating process must ensure that the optical adhesive completely covers all the dielectric microspheres and forms a uniform, bubble-free adhesive layer across the entire surface of the first glass substrate. The coating thickness is typically controlled between 5 μm and 20 μm. This thickness range must ensure that even the most prominent microspheres are adequately encapsulated, while avoiding an excessively thick adhesive layer that could increase curing stress or affect the accuracy of the optical path. The coating operation can be performed using a precision dispensing machine or a spin coater to ensure precise control of the adhesive amount and uniform distribution.

[0047] S104. Align and bond the second glass substrate with the first glass substrate coated with the optical adhesive, and encapsulate the dielectric microsphere in a sandwich structure consisting of the two glass substrates and the optical adhesive.

[0048] It should be noted that by precisely aligning the second glass substrate with the first glass substrate, which has been fixed with the dielectric microspheres and coated with an optical adhesive, the final encapsulation of the dielectric microspheres can be completed.

[0049] The alignment and bonding process requires extremely high precision to ensure encapsulation quality. Specifically, under the visual assistance of an optical microscope, the two substrates are placed on a precision displacement platform. By fine-tuning the platform, the relative positioning accuracy of the two glass substrates is controlled to be no greater than 10 μm. This ensures that the dielectric microspheres are accurately encapsulated in the preset positions, avoiding lateral misalignment that could affect the spatial accuracy of the calibration board. Simultaneously, the edge alignment deviation of the two substrates must be controlled to be no greater than 50 μm. This not only considers the neatness of the product's appearance but also ensures uniform stress distribution throughout the sandwich structure, preventing localized stress concentrations caused by uneven edges during curing, which could lead to cracking of the glass substrate or defects in the optical adhesive layer.

[0050] After precise alignment, applying a slight, uniform pressure of 0.05 to 0.1 MPa allows the second glass substrate to fall smoothly and make full contact with the optical adhesive. This also eliminates any air bubbles that may be trapped between the two substrates, ensuring that the adhesive layer is continuous and defect-free. This achieves gapless encapsulation of the dielectric microspheres, forming a sandwich structure with consistent and stable optical performance.

[0051] In this step, high-precision alignment ensures the accuracy of the simulated defect location, while bubble-free bonding ensures low-noise transmission of optical signals. Together, they enable the final calibration board to realistically and reliably simulate subsurface defects inside optical components.

[0052] S105. Curing the optical adhesive.

[0053] It should be noted that a precisely controlled curing process transforms the optical adhesive from a liquid to a solid state, ultimately forming a stable and transparent sandwich structure that encapsulates the dielectric microspheres. The choice of curing process and parameter control directly affects the internal stress, optical performance, and long-term reliability of the sandwich structure. Specifically, the curing process varies depending on the type of optical adhesive selected. If a UV-curable optical adhesive is used, it is cured by irradiation with 365nm UV light, with the light intensity controlled between 100 and 300 mW / cm² during curing. 2Within this range, the curing time is 30-120 seconds. This process has the advantages of fast curing speed and high efficiency. During this process, it is necessary to ensure that the ultraviolet light can evenly irradiate the entire optical adhesive area to ensure full cross-linking and curing, avoiding uneven internal stress caused by local uncured or over-cured areas. If a thermosetting optical adhesive is used, the entire component needs to be placed in a constant temperature environment of 60-80℃ and kept at that temperature for 1-2 hours. The thermosetting process is relatively gentle, which helps to reduce internal stress. It should be noted that after curing, the component needs to be cooled to room temperature with the oven at a slow cooling rate of 5-10℃ / min. There is a difference in the coefficient of thermal expansion between glass and optical adhesive. If the cooling is too fast, the different shrinkage rates of the adhesive layer and glass will generate internal stress, leading to substrate cracking or adhesive layer debonding. Controlling this cooling rate allows both to shrink synchronously, eliminating internal stress.

[0054] In addition, post-processing is required after curing, including edge treatment and surface cleaning. Edge treatment involves carefully wiping with solvents such as anhydrous ethanol to remove excess adhesive that overflowed from the edges of the interlayer during curing. Further, chamfering can be performed, with the chamfer size controlled between 0.5 and 1 mm. This not only improves the product's appearance but also eliminates sharp edges, preventing chipping or scratches to operators and testing equipment during use and handling. Surface cleaning involves carefully wiping the outer surfaces of the first and second glass substrates with a lint-free cloth soaked in high-purity isopropyl alcohol. This thoroughly removes any fingerprints, dust, or other contaminants that may have remained from previous processes, ensuring the calibration plate has a clean optical surface that will not affect the accuracy of subsequent defect detection.

[0055] It should also be noted that the sandwich microsphere calibration plate fabricated by the method of this application is mainly used for sensitivity calibration, resolution calibration, and defect identification capability verification of optical detection systems (such as laser scattering detection systems, dark-field imaging systems, confocal microscopes, etc.). Specifically, the fabricated calibration plate is placed on the sample stage of the optical detection system, and the system focal length is adjusted to clearly image the sandwich plane where the dielectric microspheres are located. The detection system is started, and the calibration plate is illuminated by an illumination source (such as a laser beam or broadband light source), and the system's detector receives the scattered light signal or image pattern generated by the dielectric microspheres.

[0056] During this detection process, because the dielectric microspheres are encapsulated under the second glass substrate, the detection signal must penetrate a certain thickness of glass material before it can be received by the detector. This optical path environment realistically simulates the scenario when the detection system detects subsurface defects tens to hundreds of micrometers deep inside actual optical components. Therefore, the system parameters (such as focal length and sensitivity) calibrated using this calibration plate have higher accuracy for detecting deep defects in real workpieces, overcoming the limitation of traditional thin-film calibration plates that can only simulate extremely shallow surface defects. Based on the precise refractive index matching (difference ≤ 0.03) between the first glass substrate, the optical adhesive layer, and the second glass substrate, the reflection and stray light at the interlayer interface are reduced to extremely low levels. This makes the effective scattered signal from the dielectric microspheres in the signal collected by the detector extremely pure, significantly improving the signal-to-noise ratio. The system can more clearly distinguish the weak signals of hundreds of nanometer-scale defects from background noise, thereby achieving accurate calibration of the detection system's ultimate sensitivity. Furthermore, the fully sandwiched encapsulated structure isolates the microspheres from the external environment, preventing them from detaching or shifting due to wiping, vibration, or environmental changes. This ensures that the calibration plate provides excellent repeatability and stability of the calibration signal throughout its entire lifespan, guaranteeing the long-term reliability of the testing system's calibration results and solving the problems of easy microsphere detachment and signal drift in traditional implantable calibration plates.

[0057] The method provided in this embodiment successfully fabricates a high-performance subsurface defect calibration plate by constructing a sandwich structure of two glass substrates encapsulating an optical adhesive and dielectric microspheres. This calibration plate solves the problems of easy microsphere detachment, insufficient subsurface depth, and uniform particle size in existing technologies. Furthermore, the sandwich encapsulation structure completely seals the dielectric microspheres internally, ensuring they remain firmly fixed even after high-temperature and high-humidity testing, thus guaranteeing the long-term stability and reliability of the calibration signal. By using a second glass substrate with a thickness of 0.1mm to 0.3mm and an optical adhesive layer to jointly construct a subsurface space with controllable depth, the microspheres are encapsulated at depths of tens to hundreds of micrometers below the surface, realistically simulating deep defects in actual optical components. It should also be noted that the subsurface defect calibration plate fabricated by this method supports the integration of microspheres of various particle sizes on the same calibration plate, enabling multi-range calibration on a single plate, improving applicability and detection efficiency. Refractive index matching and interface control effectively reduce stray light interference, ensuring a high signal-to-noise ratio for the calibration signal.

[0058] For better illustration, this application also provides the following specific embodiments:

[0059] Specific Example 1: Method for Fabricating an SSD Calibration Board Based on Silica Microspheres

[0060] S1: Fused silica glass, grade JGS2, is selected as the first and second glass substrates. The dimensions are 30mm x 30mm, the thicknesses of the first and second glass substrates are 2mm and 0.1mm respectively, the surface finish is grade IV, and the refractive index is 1.46. The two substrates are sequentially ultrasonically cleaned with deionized water for 12 minutes (power 250W), oxygen plasma cleaned for 6 minutes (power 100W), and dried with nitrogen.

[0061] S2: Silica microspheres with particle sizes of 500 nm, 1 μm, and 2 μm were selected, and the particle size deviation was ≤3%. The microspheres of the three particle sizes were dispersed in anhydrous ethanol / propylene glycol methyl ether acetate mixture to prepare three microsphere dispersions with a concentration of 0.5 wt%. Each dispersion was ultrasonically treated for 15 minutes.

[0062] S3: Divide the surface of the first glass substrate into three 10mm×30mm regions, corresponding to the three microsphere dispersions respectively; coat them by spin coating at 2000 rpm for 15 seconds; after coating, dry them in an 80℃ oven for 15 minutes, and the microsphere distribution density is 100 particles / mm2.

[0063] S4: Apply UV-curable optical adhesive, model NOA63, refractive index 1.48, using a dispensing machine to apply with a thickness of 10μm to ensure complete coverage of all microspheres;

[0064] S5: With the aid of an optical microscope and a precision displacement platform, the alignment deviation between the two substrate edges is 25μm. Apply 0.08MPa pressure for 10 seconds to remove air bubbles.

[0065] S6: UV curing, wavelength 365nm, light intensity 200mW / cm², time 60 seconds; wipe the excess adhesive at the edges with anhydrous ethanol, and clean the outer surface with isopropanol to obtain the SSD calibration board based on silica microspheres.

[0066] Specific Implementation Example 2: Method for Fabricating an SSD Calibration Plate Based on Polystyrene Microspheres

[0067] S1: K9 optical glass is selected as the first and second glass substrates, with a length and width of 40mm×40mm. The thickness of the first and second glass substrates is 1.5mm and 0.1mm, respectively. The surface finish is IV and the refractive index is 1.51. The pretreatment is the same as S1 in specific embodiment 1.

[0068] S2: Polystyrene microspheres with particle sizes of 100 nm, 2 μm, and 10 μm were selected, and the particle size deviation was ≤4%. The microspheres of the three particle sizes were dispersed in anhydrous ethanol / propylene glycol methyl ether acetate mixture to prepare three microsphere dispersions with a concentration of 0.8 wt%. Each dispersion was ultrasonically treated for 20 minutes.

[0069] S3: Divide the surface of the first glass substrate into three 13mm×40mm regions, corresponding to the three microsphere dispersions respectively; use a spray coating method with a pressure of 0.2MPa, a spraying distance of 8cm, and a spraying rate of 0.8mL / min; after coating, place in a 70℃ oven to dry for 18 minutes, and the microsphere distribution density is 80 particles / mm².

[0070] S4: Apply thermosetting optical adhesive, model EPO-TEK301, refractive index 1.50, with uniform coating thickness;

[0071] S5: Magnified by an optical microscope, and adjusted with a precision displacement platform, the alignment deviation of the two substrate edges is 35μm, and the microspheres are completely encapsulated after bonding;

[0072] S6: Thermosetting at 70°C for 1.5 hours with a cooling rate of 8°C / min; post-treatment is the same as S6 in Specific Example 1, to obtain an SSD calibration plate based on polystyrene microspheres.

[0073] To better verify the effectiveness of the specific embodiments, the test results of the calibration board fabricated in Specific Embodiment 1 are also provided below:

[0074] Microsphere size and distribution detection:

[0075] Figure 2 For the test result diagram of the calibration plate made in specific embodiment 1 shown in this application, please refer to... Figure 2 In specific embodiment 1, the actual particle size of the 1μm silica microspheres was 1.1μm with a deviation of 0.1μm, and the actual particle size of the 2μm microspheres was 1.9μm with a deviation of 0.1μm. When the two calibration plates were placed in an environment of 60℃ and 90% humidity for 72 hours, the adhesive did not crack and the microspheres did not fall off.

[0076] Example 2

[0077] Corresponding to the aforementioned embodiment of a method for manufacturing a sandwich microsphere calibration plate, this application also provides an embodiment of a sandwich microsphere calibration plate.

[0078] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the sandwich microsphere calibration plate provided in this application. Please refer to... Figure 3 The calibration board provided in this embodiment includes:

[0079] First glass substrate 4;

[0080] The second glass substrate 1 is disposed opposite to the first glass substrate 4, and the thickness of the second glass substrate 1 is less than that of the first glass substrate 4;

[0081] The dielectric microspheres 3 are disposed between the first glass substrate 4 and the second glass substrate 1;

[0082] An optical adhesive layer 2 is filled between the first glass substrate 4 and the second glass substrate 1, and the dielectric microspheres 3 are encapsulated and fixed therein to form a sandwich structure.

[0083] For details, please refer to the preceding description; they will not be repeated here.

[0084] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for manufacturing a sandwich microsphere calibration plate, characterized in that, The method includes: After cleaning the first glass substrate and the second glass substrate, they are dried with nitrogen gas for later use; wherein the thickness of the second glass substrate is less than the thickness of the first glass substrate, and the thickness of both the first glass substrate and the second glass substrate is less than 3 mm. After coating a microsphere dispersion onto one side surface of the first glass substrate, the substrate is dried to fix the particulate media microspheres on one side surface of the first glass substrate. An optical adhesive is coated on one side surface of the first glass substrate on which the dielectric microspheres are fixed; The second glass substrate is aligned and bonded to the first glass substrate coated with the optical adhesive, and the dielectric microsphere is encapsulated in a sandwich composed of the two glass substrates and the optical adhesive. Curing the optical adhesive; Wherein, the length and width dimensions of the first glass substrate and the second glass substrate are the same, the thickness of the second glass substrate is less than the thickness of the first glass substrate; the thickness of the first glass substrate is 1mm~3mm, the thickness of the second glass substrate is 0.1mm~0.3mm, and the difference in refractive index between the two substrates is ≤0.

02. The optical adhesive has a refractive index of 1.45~1.55, and the difference between its refractive index and that of the first glass substrate and the second glass substrate is no greater than 0.

03. The coating thickness is 5~20μm.

2. The method according to claim 1, characterized in that, Before the drying process following coating the microsphere dispersion onto one side surface of the first glass substrate, the following steps are included: The medium microspheres are dispersed in a mixed solvent to form a microsphere dispersion.

3. The method according to claim 2, characterized in that, The process of dispersing the medium microspheres in a mixed solvent to form a microsphere dispersion includes: The media microspheres were dispersed in a mixed solvent consisting of anhydrous ethanol and propylene glycol methyl ether acetate. The mixed liquid is subjected to ultrasonic treatment to obtain a microsphere dispersion; wherein the volume ratio of anhydrous ethanol to propylene glycol methyl ether acetate is 1:1 to 3:1, and the concentration of the microsphere dispersion is 0.1 to 1 wt%.

4. The method according to claim 1, characterized in that, The medium microspheres include at least silica microspheres, polystyrene microspheres, and polymer microspheres; the particle size of the medium microspheres is 100 nm to 10 μm, the particle size deviation is ≤5%, and at least three different particle sizes of the medium microspheres are fixed on the surface of the first glass substrate.

5. The method according to claim 1, characterized in that, The coating of the microsphere dispersion onto one side surface of the first glass substrate includes at least spin coating and spray coating methods; wherein, when spin coating is used, the spin coating speed is controlled at 1500~2500 rpm and the spin coating time is 10~20 seconds; when spray coating is used, the spray coating pressure is controlled at 0.1~0.3MPa, the spraying distance is 5~10cm, and the spraying rate is 0.5~1mL / min.

6. The method according to claim 1, characterized in that, The step of aligning and bonding the second glass substrate with the first glass substrate coated with the optical adhesive includes: Under an optical microscope, the relative positions of the two glass substrates are adjusted by a displacement platform, wherein the positioning accuracy of the two glass substrates is no greater than 10 μm; The edge alignment deviation of the two glass substrates is controlled to be no greater than 50 μm.

7. The method according to claim 1, characterized in that, The curing of the optical adhesive includes: When the optical adhesive is UV-curable, it is cured with UV light with a wavelength of 365nm, the curing light intensity is controlled at 100~300mW / cm², and the curing time is 30~120 seconds; When the optical adhesive is thermosetting, it is cured at 60~80℃ for 1~2 hours and cooled at a rate of 5~10℃ / min.

8. The method according to claim 1, characterized in that, After curing the optical adhesive, the method further includes: The packaged body undergoes edge treatment, including removing excess adhesive from the edges and chamfering, wherein the chamfer size is 0.5~1mm; The package is surface cleaned, including wiping the outer surfaces of the two glass substrates with isopropyl alcohol.

9. A sandwich microsphere calibration plate, characterized in that, The calibration plate is manufactured based on the manufacturing method according to any one of claims 1-8, and the calibration plate comprises: First glass substrate; A second glass substrate is disposed opposite to the first glass substrate, and the thickness of the second glass substrate is less than that of the first glass substrate; Medium microspheres are disposed between the first glass substrate and the second glass substrate; An optical adhesive layer is filled between the first glass substrate and the second glass substrate, and the dielectric microspheres are encapsulated and fixed therein to form a sandwich structure.

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