A processing method for flat glass and flat glass

Abstract

This application provides a method for processing planar glass and the planar glass itself. The method includes the following steps: thinning two opposing surfaces of the planar glass in its thickness direction until the thickness of the planar glass is greater than a set thickness H1; measuring the thickness of the planar glass using single-frequency laser interferometry to determine the actual thickness H2 of the planar glass; and etching the planar glass using an ion beam etching process, with an etching depth H = H2 - H1. In the above technical solution, the actual thickness of the planar glass is measured using single-frequency laser interferometry, and the etching thickness is determined based on the difference between the measured actual thickness and the set thickness. Then, the planar glass is etched using an ion beam etching process. Single-frequency laser measurement has high measurement accuracy, and ion beam etching also has high precision, thus allowing the thickness dimension accuracy of the planar glass to be controlled within ±30 nm.

Description

Technical Field

[0001] The present application relates to the field of near-eye display technology, and in particular to a processing method of flat glass and flat glass. Background Art

[0002] Currently, XR (Extended Reality) is being used more and more widely, but XR devices have relatively high requirements for the dimensional accuracy of their internal components. For example, the flat glass in XR devices needs to have a relatively high-precision thickness dimension.

[0003] However, the thickness control scheme for flat glass is usually a hot forming process or a cold processing process. However, when processing flat glass with these two processing processes, the maximum thickness dimensional accuracy can only be ±0.001mm. Summary of the invention

[0004] The present application provides a flat glass processing method and flat glass, which improves the accuracy of the thickness dimension of the flat glass.

[0005] The present application provides a method for processing flat glass, which comprises the following steps:

[0006] Thinning two opposite surfaces of the flat glass in the thickness direction until the thickness of the flat glass is greater than a set thickness H1; and the difference between the thickness of the flat glass and the set thickness is between 0.001 mm and 0.002 mm;

[0007] Measuring the thickness of the flat glass by using single-frequency laser interferometry to determine the actual thickness H2 of the flat glass;

[0008] The flat glass is etched by an ion beam etching process, and the etching depth H=H2-H1.

[0009] In the above technical solution, the actual thickness of the flat glass is measured by single-frequency laser interferometry, and the etching thickness is determined according to the difference between the measured actual thickness of the flat glass and the set thickness, and then the flat glass is etched by ion beam etching. Single-frequency laser measurement has high measurement accuracy, and ion beam etching also has high precision, so that the thickness of the flat glass can be controlled within ±30nm.

[0010] In a specific implementation scheme, the measuring the thickness of the flat glass by using single-frequency laser interferometry to determine the actual thickness H2 of the flat glass specifically includes:

[0011] Determine the distance A1 from the laser probe to the carrier plate by irradiating the carrier plate with a single-frequency laser;

[0012] Placing the flat glass on the carrying plate;

[0013] Irradiating the plane glass with a single-frequency laser to determine a distance A2 from the laser probe to the plane glass;

[0014] The actual thickness H2 of the flat glass satisfies: H2=A1-A2.

[0015] In a specific possible implementation scheme, the distance A1 from the laser probe to the carrier plate is determined by irradiating the carrier plate with a single-frequency laser;

[0016] Obtaining a waveform diagram of the single-frequency laser reflected by the carrier plate;

[0017] According to the formula The distance A1 from the laser probe to the carrier plate is calculated; wherein X is the measured length; n is the refractive index of air; λ is the wavelength of the single-frequency laser in vacuum; and N is the number of light and dark changes of the interference fringes in the waveform diagram.

[0018] In a specific possible implementation scheme, the distance A2 from the laser probe to the flat glass is determined by irradiating the flat glass with a single-frequency laser; specifically:

[0019] Obtaining a waveform diagram of the single-frequency laser reflected by the plane glass;

[0020] According to the formula The distance A2 from the laser probe to the plane glass is calculated.

[0021] In a specific implementation manner, the measuring the thickness of the flat glass by using single-frequency laser interferometry to determine the actual thickness H2 of the flat glass further includes:

[0022] The single-frequency laser is calibrated.

[0023] In a specific possible implementation manner, calibrating the single-frequency laser specifically includes calibrating the single-frequency laser through a standard cavity and a gas chamber filled with an inert gas.

[0024] In a specific implementation scheme, the etching of the flat glass by an ion beam etching process, with an etching depth H=H2-H1, specifically includes:

[0025] The etching time is determined by the determined etching depth H and the energy density of the ion beam.

[0026] In a specific embodiment, the etching of the flat glass by an ion beam etching process, with an etching depth of H=H2-H1, further comprises:

[0027] While the flat glass is being etched by the ion beam, the flat glass is rotated.

[0028] In a specific embodiment, the parallelism of two opposite surfaces of the flat glass is less than 2".

[0029] In a second aspect, a flat glass is provided, wherein the flat glass is flat glass prepared by any of the processing methods described above.

[0030] In the above technical solution, the actual thickness of the flat glass is measured by single-frequency laser interferometry, and the etching thickness is determined according to the difference between the measured actual thickness of the flat glass and the set thickness, and then the flat glass is etched by ion beam etching. Single-frequency laser measurement has high measurement accuracy, and ion beam etching also has high precision, so that the thickness of the flat glass can be controlled within ±30nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a method for processing flat glass provided in an embodiment of the present application;

[0032] Figure 2-3 A schematic diagram of the flat glass processing process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0034] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should be understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] First, let’s introduce the terms involved in the embodiments of this application:

[0036] Surface shape (flatness): refers to the degree of undulation of the flat glass surface relative to the absolute plane;

[0037] Parallelism: refers to the degree of parallelism between the upper and lower surfaces of flat glass, expressed in angles;

[0038] IBE (Ion Beam Etching) is a micro-nano manufacturing technology that uses high-energy ion beams to remove the surface of materials. The principle is: an ion source generates a high-energy ion beam (usually argon ions) that hits the surface of the material vertically or at an angle; the high-energy ions collide with atoms on the surface of the material, causing the atoms to be knocked out and the material to be removed layer by layer, thereby achieving the purpose of precise size control. This etching method belongs to the physical etching process, and the physical thickness control accuracy is ≤5nm.

[0039] To facilitate understanding of the flat glass processing method provided in the embodiment of the present application, its application scenario is first described. The flat glass processing method provided in the embodiment of the present application is used to process flat glass, which is applied to XR devices, including but not limited to AR (Augmented Reality, enhanced display technology) or VR (Virtual Reality, virtual display technology) or MR (Mixed Reality, mixed reality). XR devices generate and integrate real and virtual environments through computers to create a digital environment that allows human-computer interaction.

[0040] The current control schemes for the thickness of flat glass are hot pressing or cold processing, and the above processes have low control accuracy for the thickness dimensions of flat glass. For example, when hot pressing is used, the melting and molding process controls the thickness accuracy of flat glass at ±0.1mm, and the hot pressing process controls the thickness accuracy of flat glass at ±0.1mm. In the cold processing process, when cutting flat glass, when a large outer circle cutting machine or a multi-blade cutting machine is used for cutting, the thickness dimension accuracy is ±0.2mm; when an inner circle cutting machine, a wire cutting machine, or a laser cutting machine is used for cutting, the thickness dimension accuracy is ±0.1mm; when a water jet cutting machine is used for cutting, the thickness dimension accuracy is ±0.2mm. When the surface is treated after cutting, the thickness accuracy is ±0.001mm through grinding and polishing. It can be seen from the above description that in the existing processing methods for flat glass, the highest control accuracy of the thickness dimension of flat glass can only reach ±0.001mm. ,

[0041] To this end, the present application provides a method for processing flat glass in an embodiment to improve the accuracy of the thickness of the flat glass, which will be described in detail below in conjunction with specific drawings and embodiments.

[0042] refer to Figure 1 As shown, Figure 1The flowchart of the flat glass processing method provided in the embodiment of the present application is shown. The flat glass processing method provided in the embodiment of the present application specifically comprises the following steps:

[0043] Step 001: thinning two opposite surfaces of the flat glass in the thickness direction until the thickness of the flat glass is greater than a set thickness H1;

[0044] Specifically, the above-mentioned flat glass can be prepared by different processes, for example, it can be glass formed by hot pressing or cold working.

[0045] When the flat glass is thinned, it can be processed by grinding and polishing. For the convenience of description, the two surfaces of the flat glass opposite to each other along the thickness direction are defined as the first surface and the second surface.

[0046] like Figure 2 As shown, first, the second surface 12 of the flat glass 10 is fixed on the reference seat 100, and then the first surface 11 of the flat glass 10 is ground and polished. When the second surface 12 of the flat glass 10 is fixed on the reference seat 100, the second surface 12 of the flat glass 10 can be fixed on the reference seat 100 through the adhesive layer 20. The reference seat 100 has a supporting surface, the adhesive layer 20 is coated on the supporting surface, and then the flat glass 10 is placed on the supporting surface to fix the flat glass 10 through the adhesive layer 20. The above-mentioned adhesive layer 20 can be an adhesive glue or a wax layer.

[0047] When the first surface 11 is ground and polished, the flatness of the first surface 11 needs to be ≤λ / 20, where λ=632.8nm (laser light source wavelength of the laser plane interferometer). This allows the first surface 11 to have a high flatness, which is convenient for subsequent thickness measurement of the flat glass 10. The flatness of the first surface 11 can be any flatness less than λ / 20, such as λ / 20, λ / 21, λ / 25, λ / 30, λ / 40, etc.

[0048] refer to Figure 3 After the first surface 11 is ground and polished, the flat glass 10 is turned over, the first surface 11 of the flat glass 10 is optically bonded to the reference seat 100, and the second surface 12 of the flat glass 10 is ground and polished. The optical bonding is a connection method, which is specifically a process of adsorbing two clean, smooth and consistent optical parts together by applying pressure without using an adhesive. In the embodiment of the present application, the flat glass 10 can be pressed and adsorbed on the reference seat 100 by the optical bonding connection method, thereby achieving the fixation of the flat glass 10.

[0049] The second surface 12 is ground and polished at least once until the difference between the second surface 12 and the reference seat 100 is greater than the set thickness H1. The difference between the thickness of the flat glass and the set thickness is between 0.001 mm and 0.002 mm.

[0050] After grinding and polishing the second surface 12, by measuring the difference between the second surface 12 and the reference seat 100 until the difference is greater than the set thickness H1, the thickness of the flat glass 10 can be H1+0.001mm, H1+0.0015mm, H1+0.002mm. Since the second surface 12 is directly attached to the support surface of the reference seat 100, during the measurement process, the thickness of the thinned flat glass 10 can be determined by directly measuring the difference between the second surface 12 and the support surface of the reference seat 100, so that the accurate thickness of the flat glass 10 can be obtained. It should be understood that the above-mentioned grinding and polishing of the second surface 12 at least once until the difference between the second surface 12 and the reference seat 100 is greater than the set thickness H1 means that after grinding and polishing the second surface 12 once, the difference between the second surface 12 and the support surface of the reference seat 100 is measured to be greater than the set thickness.

[0051] When grinding and polishing the second surface 12, it is necessary to achieve a flatness of the second surface 12 ≤ λ / 20, so that the second surface 12 has a high flatness. The flatness of the second surface 12 can be λ / 20, λ / 21, λ / 25, λ / 30, λ / 40, or any flatness less than λ / 20.

[0052] In addition, when grinding and polishing the flat glass, the surface parallelism of the two opposite surfaces of the flat glass is less than 2". That is, the surface parallelism of the first surface 11 and the second surface 12 is less than 2". That is, the first surface 11 and the second surface 12 have a high degree of parallelism to ensure the accuracy of the thickness of the flat glass 10. Among them, the surface parallelism of the first surface 11 and the second surface 12 can be 1.9", 1.8", 1.5", 1", 0.5", etc., any parallelism less than 2".

[0053] It should be understood that when the first surface 11 and the second surface 12 are ground and polished to achieve thinning, the thickness of the thinned flat glass 10 is greater than the set thickness H1. The thinning amount can be determined based on the actual thickness of the flat glass 10 and the set thickness, and both the first surface 11 and the second surface 12 need to be thinned to obtain higher surface parallelism and flatness for the first surface 11 and the second surface 12.

[0054] In addition, in the embodiment of the present application, there is no high requirement for the control accuracy of the thinning amount, and the processing error of the current processing equipment meets the requirement for thinning the flat glass 10 in the embodiment of the present application.

[0055] Step 002: using single-frequency laser interferometry to measure the thickness of the plane glass and determine the actual thickness H2 of the plane glass;

[0056] Specifically, in the processing method provided in the embodiment of the present application, when the thickness of the flat glass is detected, the thickness of the flat glass is detected by single-frequency laser interferometry. When the single-frequency laser interferometry is used, the measurement can be performed by a single-frequency laser interferometry measurement system. The single-frequency laser interferometry measurement system is a light beam emitted from a laser, which is divided into two paths by a beam splitter after beam expansion and collimation, and is reflected back from a fixed reflector and a movable reflector respectively and converges on the beam splitter to generate interference fringes, and the interference fringes are processed and converted to calculate relevant indicators.

[0057] The specific measurement may include the following steps:

[0058] Step a: Irradiate the carrier plate with a single-frequency laser to determine the distance A1 from the laser probe to the carrier plate;

[0059] Specifically, when measuring the distance A1, the measurement is performed using a waveform diagram of a single-frequency laser. The measurement specifically includes the following steps:

[0060] Step 01: Obtain the waveform of the single-frequency laser reflected by the carrier plate;

[0061] Specifically, the plane glass is measured by emitting a laser beam, and the interference signal is input into the FPGA interference signal processing module for processing, so as to obtain an accurate waveform diagram. FPGA (Field Programmable Gate Array) is a product further developed on the basis of programmable devices such as PAL (programmable array logic) and GAL (generic array logic). It appears as a semi-custom circuit in the field of application-specific integrated circuits, which not only solves the shortcomings of custom circuits, but also overcomes the shortcomings of the limited number of gate circuits of the original programmable device. The FPGA interference signal processing module used in the embodiment of the present application is used to process the interference signal, and realize the phase subdivision and error correction of the interference signal, so as to obtain a more accurate waveform diagram. It should be understood that the above-mentioned signal phase subdivision and error correction are common waveform diagram processing methods in the field, and processing the waveform diagram through the FPGA interference signal processing module is also a common processing method in the field, which will not be described in detail here.

[0062] Step 02: According to the formula Calculate the distance A1 from the laser probe to the carrier plate;

[0063] Specifically, when calculating the distance A1 from the laser probe to the carrier plate, the formula Calculate, where X is the measured length; n is the refractive index of air; λ is the wavelength of the single-frequency laser in vacuum; and N is the number of bright and dark changes of the interference fringes in the waveform. That is, when measuring A1, X=A1.

[0064] Step b: placing the flat glass on the carrier plate;

[0065] Specifically, the flat glass is fixed on the carrier plate. In an implementable solution, the flat glass is also fixed on the carrier plate by optical adhesive so that the carrier plate and the flat glass fit tightly together to avoid the gap between the two affecting the measurement accuracy.

[0066] Step c: Irradiate the flat glass with a single-frequency laser to determine the distance A2 from the laser probe to the flat glass;

[0067] Specifically, the measurement method of step c is the same as that of step a. In step c, the waveform of the single-frequency laser reflected by the plane glass is also obtained first, and then according to the formula The distance A2 from the laser probe to the plane glass is calculated. For details, please refer to the relevant descriptions in the above steps 01 to 02, which will not be repeated here.

[0068] Step d: The actual thickness H2 of the flat glass satisfies: H2 = A1 - A2.

[0069] Specifically, after measuring the distance A1 from the laser probe to the carrier plate and the distance A2 from the laser probe to the flat glass, the actual thickness H2 of the flat glass can be obtained according to the formula H2=A1-A2.

[0070] It should be understood that when using a single-frequency laser for detection, it is necessary to ensure the stability of the laser. Therefore, when using a single-frequency laser for measurement, the single-frequency laser is also calibrated. Specifically, the single-frequency laser can be calibrated through a standard cavity and a gas chamber filled with inert gas.

[0071] During specific detection, single-frequency lasers can be monitored in real time. Exemplarily, the single-frequency laser beam emitted by the laser is divided into three beams, one of which is transmitted to the laser probe through an optical fiber for distance measurement. Another beam is used to emit to the air chamber, and the third beam is transmitted to the standard cavity. During monitoring, two sensors are used to receive the laser passing through the air chamber and the laser passing through the standard cavity, respectively, and the received signal is compared with the set signal. When any received signal exceeds the range of the set signal, it is determined that the single-frequency laser is unstable and needs to be calibrated. After calibrating the laser, distance measurement is performed again, and real-time monitoring is performed during the distance measurement process.

[0072] Step 003: Etch the flat glass by ion beam etching process, with the etching depth H=H2-H1.

[0073] Specifically, during etching, an ion source generates a high-energy ion beam (usually argon ions) to impact the surface of the material vertically or at an oblique angle; the high-energy ions collide with the atoms on the surface of the material, causing the atoms of the flat glass to be knocked out, and the material is removed layer by layer, thereby achieving the purpose of precise size control, and its physical thickness control accuracy is: ≤5nm.

[0074] As can be seen from the above description, the energy density of the ion beam is directly related to the etching thickness. Therefore, before etching, the etching time is determined by determining the etching depth H and the energy density of the ion beam, so as to ensure that the etching thickness meets the requirements.

[0075] In addition, when etching the flat glass by ion beam, the flat glass is rotated, wherein the axis around which the flat glass rotates is along the emission direction of the ion beam. Since the ion beam is a normal distribution, when the flat glass is rotated, the etching can be made more uniform.

[0076] In the above technical solution, the actual thickness of the flat glass is measured by single-frequency laser interferometry, and the etching thickness is determined according to the difference between the measured actual thickness of the flat glass and the set thickness, and then the flat glass is etched by ion beam etching. Single-frequency laser measurement has high measurement accuracy, and ion beam etching also has high precision, so that the thickness of the flat glass can be controlled within ±30nm.

[0077] After etching the flat glass, the size of the processed flat glass can be measured again by the single-frequency laser system to confirm whether the thickness of the flat glass meets the requirements. For the specific measurement method, please refer to the above step 002.

[0078] The embodiment of the present application also provides a flat glass, which is a flat glass prepared by any of the above-mentioned processing methods.

[0079] In the above technical scheme, the actual thickness of the flat glass is measured by single-frequency laser interferometry, and the etching thickness is determined according to the difference between the measured actual thickness of the flat glass and the set thickness, and then the flat glass is etched by ion beam etching. Single-frequency laser measurement has a high measurement accuracy, and ion beam etching also has a high precision. In the above steps, the surface of the flat glass is polished with high precision to control the consistency of the thickness of the upper and lower surfaces of the flat glass. At this time, the consistency accuracy of the thickness of the flat glass is 20 to 30nm. In addition, the interference signal is processed by the FPGA interference signal processing module to realize signal phase subdivision and error correction. The measurement system accuracy is ±5nm; the tested flat glass is removed from the surface of the material by IBE, and the IBE physical thickness control accuracy is: ≤5nm; the above three key process schemes are used to process high-precision thickness glass flat sheets, and the thickness accuracy can reach ±30nm.

[0080] The embodiment of the present application also provides a near-eye display device, in which the glass component adopts the above-mentioned flat glass.

[0081] It can be seen from the above processing method that the flat glass has a high thickness accuracy, which can improve the accuracy of the components in the near-eye display device, and further improve the optical performance of the near-eye display device.

[0082] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this disclosure.

[0083] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for processing flat glass, characterized in that: The following steps are involved: Thinning two opposite surfaces of the flat glass in the thickness direction until the thickness of the flat glass is greater than a set thickness H1; and the difference between the thickness of the flat glass and the set thickness is between 0.001 mm and 0.002 mm; Measuring the thickness of the flat glass by using single-frequency laser interferometry to determine the actual thickness H2 of the flat glass; The flat glass is etched by an ion beam etching process, and the etching depth H=H2-H1.

2. The method for processing flat glass according to claim 1, characterized in that: The method of measuring the thickness of the flat glass by using single-frequency laser interferometry to determine the actual thickness H2 of the flat glass specifically includes: Determine the distance A1 from the laser probe to the carrier plate by irradiating the carrier plate with a single-frequency laser; Placing the flat glass on the carrying plate; Irradiating the plane glass with a single-frequency laser to determine a distance A2 from the laser probe to the plane glass; The actual thickness H2 of the flat glass satisfies: H2=A1-A2.

3. The method for processing flat glass according to claim 2, characterized in that: The single-frequency laser is used to irradiate the carrier plate to determine the distance A1 from the laser probe to the carrier plate; Obtaining a waveform diagram of the single-frequency laser reflected by the carrier plate; According to the formula The distance A1 from the laser probe to the carrier plate is calculated; wherein X is the measured length; n is the refractive index of air; λ is the wavelength of the single-frequency laser in vacuum; and N is the number of light and dark changes of the interference fringes in the waveform diagram.

4. The method for processing flat glass according to claim 3, characterized in that: The single-frequency laser is used to irradiate the flat glass to determine the distance A2 from the laser probe to the flat glass; specifically: Obtaining a waveform diagram of the single-frequency laser reflected by the plane glass; According to the formula The distance A2 from the laser probe to the plane glass is calculated.

5. The method for processing flat glass according to claim 2, characterized in that: The method of measuring the thickness of the flat glass by using single-frequency laser interference to determine the actual thickness H2 of the flat glass further includes: The single-frequency laser is calibrated.

6. The method for processing flat glass according to claim 5, characterized in that: The calibrating the single-frequency laser specifically includes calibrating the single-frequency laser through a standard cavity and a gas chamber filled with an inert gas.

7. The method for processing flat glass according to any one of claims 1 to 6, characterized in that: The etching of the flat glass by an ion beam etching process, with an etching depth H=H2-H1, specifically includes: The etching time is determined by the determined etching depth H and the energy density of the ion beam.

8. The method for processing flat glass according to claim 7, characterized in that: The etching of the flat glass by an ion beam etching process, with an etching depth of H=H2-H1, further comprises: While the flat glass is being etched by the ion beam, the flat glass is rotated.

9. The method for processing flat glass according to claim 8, characterized in that: The plane parallelism of two opposite surfaces of the flat glass is less than 2″.

10. A flat glass, characterized in that: The flat glass is flat glass prepared by the processing method according to any one of claims 1 to 9.

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