Cvd diamond with microlens array and method of processing the same

Abstract

The application discloses CVD diamond with a microlens array and a processing method thereof, and the method comprises the following steps: polishing a processing surface of a diamond substrate to a surface roughness of less than 2 nm, and dividing the polished processing surface into several quadrant regions; point-by-point ablation of the processing surface is performed by means of a femtosecond laser to obtain a microlens array composed of several arranged microlens units; raster scanning is performed on the surface of the microlens array to form a nanometer grating layer on the surface of each microlens unit; different linear polarization directions are used for raster scanning in the several quadrant regions; and the processed diamond substrate is subjected to ultrasonic cleaning to obtain the CVD diamond with the microlens array. The application produces bright and dark flickering through the microlens array, produces color gradient through the nanometer grating layer, and realizes the multi-color effect by using different linear polarization directions in different regions, thereby solving the problem of single visual effect of the planar CVD diamond.

Description

Technical Field

[0001] This application relates to the field of diamond processing technology, and in particular to a CVD diamond with a microlens array and a processing method thereof. Background Technology

[0002] Chemical vapor deposition (CVD) synthetic diamonds, with their extremely high hardness, excellent thermal conductivity, and good visible and near-infrared transmittance, have become decorative materials for wearable devices such as smart rings and smartwatches. With the rapid development of the wearable electronics industry, CVD diamonds are receiving increasing market attention as decorative materials for product surfaces.

[0003] In the context of increasingly fierce competition in the consumer electronics market, consumers are no longer satisfied with smart wearable devices that only have basic health monitoring and data interaction functions. They are demanding higher levels of personalization, dynamism, and a premium feel in their appearance. As the most direct visual element of products such as smart rings, the surface finish of the optical window directly determines the overall quality of the product.

[0004] However, current planar CVD diamond sheets used in wearable devices generally suffer from a lack of visual variety and dynamic variation, making it difficult to simultaneously meet the dual requirements of functionality and aesthetics. Existing CVD diamond processing methods cannot effectively endow planar diamond sheets with rich dynamic optical effects without affecting their core properties such as optical transmittance and mechanical strength, thus limiting the further application of CVD diamonds in high-end wearable devices and the enhancement of product added value. Summary of the Invention

[0005] This application provides a CVD diamond and its processing method, which solves the problem of the single optical effect of planar CVD diamonds by dividing the processing surface into sections and processing nanograting layers with different polarization directions.

[0006] The first aspect of this application provides a method for processing CVD diamonds, the method comprising:

[0007] The surface of the diamond matrix is ​​polished until the surface roughness is less than 2nm, and the polished surface is divided into several quadrant regions. The processing surface is ablated point by point using a femtosecond laser to obtain a microlens array composed of several arranged microlens units; The surface of the microlens array is scanned by a grating to form a nanograting layer on the surface of each microlens unit; wherein, different linear polarization directions are used for grating scanning in the several quadrant regions. The processed diamond matrix is ​​ultrasonically cleaned to obtain a CVD diamond with a microlens array.

[0008] Optionally, the step of ablating the processed surface point by point with a femtosecond laser to obtain a microlens array composed of a plurality of arranged microlens units includes: The microlens unit is ablated point by point from the edge to the center using a concentric circle scanning method, and the depth of each ablation point is controlled within a preset range by controlling the single pulse energy of the femtosecond laser. By adjusting the scanning radius of the concentric circles and the number of pulses at each ablation point, the radius of curvature and diameter of the microlens unit are controlled within a preset range to obtain a single microlens unit. According to a preset arrangement, the formation process of the individual microlens unit is repeated at different positions on the processing surface, so that several microlens units are arranged regularly to obtain a microlens array.

[0009] Optionally, the step of ablation point by point along the edge of each microlens unit in the microlens array towards the center using a concentric circle scanning method, and controlling the depth of each ablation point within a preset range by controlling the single-pulse energy of the femtosecond laser, includes: The energy of a single pulse of a femtosecond laser is controlled so that each laser pulse forms an ablation point of a preset depth on the processing surface; The single pulse energy is adjusted according to the correspondence between the single pulse energy and the depth of the ablation point, so that the actual depth of each ablation point falls within the target depth range. Each ablation point distributed along the concentric circle trajectory is given a corresponding single pulse energy, so that each ablation point distributed along the concentric circle trajectory has the same depth, or the depth of each ablation point varies in a stepwise manner with the radius of the concentric circle.

[0010] Optionally, the step of performing grating scanning on the surface of the microlens array to form a nanograting layer on the surface of each microlens unit, wherein grating scanning is performed using different linear polarization directions in the plurality of quadrant regions, includes: For each of the plurality of quadrant regions, the linear polarization direction of the femtosecond laser is set to a preset angle, and the preset angles of the plurality of quadrant regions are different from each other; Under the set linear polarization direction, the surface of the microlens array is scanned by a grating, so that a nano-grating layer with a corresponding grating orientation is formed on the surface of each microlens unit. Raster scanning is performed sequentially on each of the aforementioned quadrant regions until all quadrant regions have been scanned.

[0011] Optionally, forming a nanograting layer with a corresponding grating orientation on the surface of each of the microlens units further includes: By adjusting the linear polarization direction of the femtosecond laser, the grating orientation of the nanograting layer is controlled so that the grating orientation is perpendicular to the linear polarization direction.

[0012] Optionally, dividing the polished surface into several quadrant regions includes: marking cross-shaped dividing lines on the polished surface to divide the surface into four quadrant regions of equal area.

[0013] The second aspect of this application provides a CVD diamond, which is obtained by the processing method described in any one of the first aspects of this application.

[0014] Optionally, the CVD diamond includes: a diamond matrix, a microlens array, and a nanograting layer; The microlens array is formed on the machined surface of the diamond matrix, and the microlens array is composed of a number of regularly arranged microlens units; The nanograting layer is formed on the surface of each of the microlens units.

[0015] Optionally, the diameter of the microlens unit is 5-100 μm, the radius of curvature is 10-500 μm, and the spacing between adjacent microlens units is 0-20 μm; The period of the nanograting layer is 100-800nm, and the depth is 50-300nm.

[0016] Optionally, the microlens array includes at least two types of microlens units with different radii of curvature, and the microlens units with different radii of curvature are arranged in a preset pattern.

[0017] As can be seen from the above technical solutions, this application has the following advantages: A microlens array is first formed by point-by-point ablation of the polished diamond substrate using a femtosecond laser. Then, a nano-grating layer is fabricated on the array surface using grating scanning. During grating scanning, the processed surface is divided into several quadrant regions, each with a different linear polarization direction. The microlens array produces a flickering effect, while the nano-grating layer exhibits color gradations. The combination of these two elements causes the emitted light to carry both intensity and wavelength variations. Different quadrant regions have different grating orientations due to their different linear polarization directions, thus presenting different structural colors at the same viewing angle. When the diamond is rotated, each flickering point not only undergoes a continuous color change, but different regions also form color zoning contrasts. The entire processing has minimal heat-affected zone, effectively suppressing diamond graphitization or microcrack formation. The order of fabricating the microlens array before the nano-grating layer reduces process conflicts when combining the two structures, effectively solving the problem of monotonous visual effects and lack of dynamic variation in planar CVD diamonds, and achieving a multi-colored optical effect. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic flowchart of one embodiment of the CVD diamond processing method provided in this application; Figure 2 A schematic flowchart of an embodiment of the CVD diamond processing method provided in this application, which uses a femtosecond laser to ablate the processing surface point by point; Figure 3 A schematic flowchart of an embodiment of the CVD diamond processing method provided in this application, which involves grating scanning of the surface of a microlens array; Figure 4 This is a schematic diagram of the structure of the microlens array in CVD diamond provided in this application; Figure 5 This is a schematic diagram of the cross-section of the microlens unit in CVD diamond provided in this application. Detailed Implementation

[0020] This application provides a CVD diamond and its processing method. By dividing the polished surface into several quadrant regions, a femtosecond laser is used to ablate the microlens array point by point. In each quadrant, a grating is scanned with different linear polarization directions to form a nano-grating layer. This solves the problems of single optical effect and conflict between composite processing technology in planar CVD diamonds, and realizes a dynamic effect of multi-color partitioning.

[0021] The CVD diamonds provided in this application can be applied to optical windows of wearable devices such as smart rings and smartwatches, as well as decorative parts in jewelry. Taking a smart ring as an example, the processed CVD diamond is fitted to the top of the ring. Under natural or ambient light, the microlens array and nano-grating layer on the outer surface will exhibit a dynamic optical effect of dense shimmering accompanied by iridescent color gradients as the wearer moves their wrist, significantly enhancing the product's premium look and recognizability. The inner surface of the diamond remains smooth, not affecting near-infrared light transmission, and can simultaneously meet the signal acquisition needs of photoplethysmography sensors such as heart rate and blood oxygen sensors. At the same time, its high thermal conductivity helps to quickly dissipate heat from the sensors, preventing localized overheating of the skin. In addition, the CVD diamond can also be used in thin-plate jewelry such as pendants and earrings, allowing the flat diamond to display rich changes in brightness and color from different angles, enhancing the product's visual appeal.

[0022] This application first provides an embodiment of a CVD diamond processing method, which is described in detail below with reference to the accompanying drawings. Figure 1 , Figure 1 A schematic flowchart illustrating an embodiment of the CVD diamond processing method provided in this application, the embodiment including: S101. Polish the surface of the diamond matrix until the surface roughness is less than 2nm, and divide the polished surface into several quadrant regions. A diamond substrate is selected, which is a flat, single-crystal diamond sheet, typically between 0.3 mm and 1.0 mm thick, and has at least one optical surface to be processed. The diamond substrate is fixed on a polishing jig, and graded polishing is performed using a suspension of diamond micropowder with progressively decreasing particle size. For example, coarse polishing is first done with 3 μm diamond micropowder, followed by medium polishing with 1 μm diamond micropowder, and finally fine polishing with 0.5 μm diamond micropowder. After each polishing stage, the surface is ultrasonically cleaned with deionized water, and the surface roughness is measured until the surface roughness Ra of the processed surface is less than 2 nm, resulting in a mirror-like smooth surface.

[0023] Because nanogratings with different polarization directions need to be applied to different regions, the processed surface is divided into regions after polishing. In this embodiment, the processed surface is divided into several quadrant regions. Taking the division of the processed surface into four quadrant regions of equal area as an example: Specifically, a low-power femtosecond laser or a precision mechanical scribing needle is used to draw two mutually perpendicular straight lines along the horizontal and vertical center lines on the processed surface, forming a cross-shaped dividing line. The intersection of this cross-shaped dividing line coincides with the geometric center of the processed surface. The two straight lines divide the processed surface into four quadrant regions of equal area, which are respectively denoted as the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant. The purpose of dividing the surface into quadrants is to prepare for subsequent scanning with nanogratings of different polarization directions in different regions. It should be noted that the number of quadrant regions is not limited to four; it can be two, three, or more depending on the design requirements.

[0024] S102. The processing surface is ablated point by point by femtosecond laser to obtain a microlens array composed of several arranged microlens units. A polished and quadrant-divided CVD diamond substrate is fixed on a femtosecond laser processing platform. The pulse width of the femtosecond laser is set to the femtosecond range, and the repetition frequency is in the range of hundreds of kilohertz to megahertz. During processing, the laser beam is focused on the processing surface and ablates each microlens unit to be formed point by point according to a preset scanning path. Specifically, for a single microlens unit, a concentric circle scanning strategy is adopted: starting from the edge of the microlens, the laser moves towards the center along a concentric circle trajectory, with multiple laser ablation points distributed on each circumference. By controlling the position and depth of each ablation point, material is removed layer by layer, ultimately forming a concave or convex microlens with a smooth curved surface. On the entire processing surface, the above process is repeated in a hexagonal close-packed or square arrangement, so that thousands or even tens of thousands of microlens units are regularly distributed throughout the processing surface, thus forming a microlens array. The radius of curvature and diameter of each microlens unit can be controlled by adjusting the scanning radius and ablation point density according to actual design requirements.

[0025] S103. Perform grating scanning on the surface of the microlens array to form a nano-grating layer on the surface of each microlens unit; wherein, grating scanning is performed in several quadrant regions using different linear polarization directions. After fabricating the microlens array, without moving the diamond substrate, the parameters of the femtosecond laser are adjusted to reduce the laser energy density to a threshold range suitable for forming nanogratings. Subsequently, a grating scan is performed on the surface of the microlens array: the laser beam moves back and forth along parallel lines, covering the entire fabricated area row by row. During the scan, the linear polarization direction of the femtosecond laser is set for several pre-divided quadrant regions, and the linear polarization direction of each region is different. For example, when divided into four quadrants, the first quadrant uses horizontal polarization at 0°, the second quadrant uses 45° polarization, the third quadrant uses vertical polarization at 90°, and the fourth quadrant uses 135° polarization. Within each region, the linear polarization direction remains unchanged, completing the grating scan of the entire area. Due to the inductive effect of the femtosecond laser, the surface of the microlens unit self-organizes to form a periodic nanoscale grating structure, i.e., a nanograting layer. The stripe direction of this grating layer is perpendicular to the linear polarization direction used in the current scan. Different quadrants obtain nanogratings with different orientations due to their different polarization directions, thus exhibiting different structural colors in different regions at the same observation angle.

[0026] S104. The processed diamond matrix is ​​ultrasonically cleaned to obtain a CVD diamond with a microlens array.

[0027] After the laser processing described above, the diamond surface may retain micron- or nano-sized debris, carbides, or unremoved processing products. The processed diamond substrate is then sequentially immersed in acetone, anhydrous ethanol, and deionized water, undergoing ultrasonic cleaning for 5 to 15 minutes in each solvent. Ultrasonic cleaning removes surface-attached particles without damaging the formed microlens array and nanograting layer. After cleaning, the diamond surface is dried with high-purity nitrogen gas to obtain the finished CVD diamond.

[0028] The CVD diamonds produced have a microlens array on their surface and a nanograting layer superimposed on it, with different grating orientations in each quadrant. Under natural or ambient light, the microlens array produces alternating bright and dark shimmering spots, and the nanograting layer causes each spot to change color from blue to red as the viewing angle changes. At the same time, due to the different grating orientations, each quadrant exhibits different structural colors at the same viewing angle, forming a rich optical effect of zoned multicolors and dynamic changes.

[0029] In this embodiment, a microlens array is first formed by point-by-point ablation of the polished diamond substrate surface using a femtosecond laser. Then, a nano-grating layer is fabricated on the array surface using grating scanning. During grating scanning, the processed surface is divided into several quadrant regions (e.g., four quadrants) with different linear polarization directions. The microlens array produces a flickering effect, while the nano-grating layer exhibits color gradients. The combination of these two elements causes the emitted light to carry both intensity and wavelength variations. Different quadrant regions have different grating orientations due to their different linear polarization directions, thus presenting different structural colors at the same viewing angle. When the diamond is rotated, each flickering point not only undergoes a continuous color change, but also forms color zoning contrasts between different regions. The entire processing has minimal heat impact, effectively suppressing diamond graphitization or microcrack formation. The order of fabricating the microlens array before the nano-grating layer reduces process conflicts when combining the two structures, effectively solving the problem of monotonous visual effects and lack of dynamic variation in planar CVD diamonds, and achieving a multi-colored optical effect.

[0030] By ablating the processing surface point by point with a femtosecond laser, a microlens array consisting of several arranged microlens units is obtained. A detailed description of the microlens array follows; please refer to [link / reference]. Figure 2 , Figure 2 A schematic flowchart of an embodiment of the CVD diamond processing method provided in this application, which involves point-by-point ablation of the processing surface using a femtosecond laser, includes: S201. The single-pulse energy of the femtosecond laser is controlled so that each laser pulse forms an ablation point of a preset depth on the processing surface. When femtosecond lasers process diamonds, each laser pulse is focused on the surface, depositing energy into the material in a very short time. This causes localized material vaporization or decomposition, forming tiny pits, or ablation points. The depth of the ablation point is mainly determined by the energy of the single pulse: higher energy results in a greater depth, and lower energy results in a smaller depth.

[0031] Based on the required surface profile of the target microlens unit, determine the preset depth range for each ablation point. For example, if a concave microlens with a depth of approximately 2.3 μm needs to be fabricated, and this microlens is formed by ablation of 15 concentric layers, then the average ablation depth of each layer is approximately 0.15 μm. Therefore, the target depth for each ablation point can be set between 0.1 μm and 0.2 μm.

[0032] Next, the femtosecond laser is tuned. By adjusting the laser's output power or attenuator, the single-pulse energy is stably controlled to a value that can produce the target depth range. For example, if a depth of approximately 0.3 μm is required for each ablation point, the single-pulse energy can be set to around 1 μJ. Before formal processing, single-point ablation is typically performed on CVD diamond test samples from the same batch at different single-pulse energies. The ablation depth is measured and recorded, and a calibration curve of energy versus depth is established to ensure accuracy during actual processing.

[0033] S202. Adjust the single pulse energy according to the correspondence between single pulse energy and ablation point depth so that the actual depth of each ablation point falls within the target depth range. Because femtosecond lasers may experience energy fluctuations, or the absorption characteristics of different regions on the diamond surface may vary slightly, real-time monitoring or open-loop calibration compensation is necessary to ensure that the actual depth of each ablation point always falls within the allowable error range. In practice, single-pulse ablation tests can be performed on diamond samples from the same batch under identical processing conditions beforehand. A series of ablation depths corresponding to single-pulse energies can be measured and recorded, and a calibration curve can be plotted. Then, based on this calibration curve, the target depth value for each ablation point is used to deduce the corresponding single-pulse energy setting. For example, if the calibration results show that a single-pulse energy of 1.5 μJ corresponds to an ablation depth of 0.10 μm, 2.0 μJ corresponds to 0.15 μm, and 2.5 μJ corresponds to 0.20 μm, then when a depth of 0.15 μm is required, the single-pulse energy is set to 2.0 μJ. If a deviation in actual depth is detected during processing, compensation can be achieved by fine-tuning the single-pulse energy through online monitoring or periodic sampling.

[0034] S203. Apply the corresponding single pulse energy to each ablation point distributed along the concentric circle trajectory, so that each ablation point distributed along the concentric circle trajectory has the same depth, or make the depth of each ablation point change in a stepwise manner with the change of the radius of the concentric circle, thereby obtaining the corresponding ablation point sequence. When forming a single microlens unit, a concentric circle scanning method is used. Specifically, the laser beam first moves circumferentially at the maximum radius of the microlens edge, generating an ablation point with each pulse. All ablation points located on the same concentric circle radius, since they are on the same height ring of the microlens surface, usually need to have the same depth to ensure a smooth surface. For concentric circle rings with different radii, the same ablation point depth can be set, or the depth can be gradually increased or decreased from the edge to the center according to a preset surface profile to form an aspherical lens.

[0035] For example, a microlens is formed by ablation of 15 concentric circles. From the edge to the center, the radius of each concentric circle gradually decreases, and the volume of material to be removed gradually increases. Therefore, the ablation depth of each layer should increase in a stepwise manner, with the outermost layer having the smallest depth (approximately 0.10 μm), the innermost layer having the largest depth (approximately 0.25 μm), and the depths of the middle layers falling between the two. This step determines the target depth at the radius of each concentric circle based on a pre-calculated surface equation, and then allocates corresponding single-pulse energy to each layer according to the calibration curve. During the scanning process, the laser outputs pulses according to the planned energy sequence, causing the ablation points distributed along the concentric circle trajectory to form according to the preset depth pattern, thereby obtaining a depth-controllable ablation point sequence.

[0036] S204. By adjusting the scanning radius of the concentric circles and the number of pulses at each ablation point, the radius of curvature and diameter of the microlens unit are controlled within a preset range to obtain the microlens unit. The maximum scanning radius of the concentric circles determines the diameter of the microlens unit. For example, to obtain a microlens with a diameter of 30 μm, the maximum scanning radius is set to 15 μm; to obtain a microlens with a diameter of 50 μm, the maximum scanning radius is set to 25 μm. By setting the maximum scanning radius, the diameter of the microlens unit can be controlled within the target range.

[0037] Meanwhile, the number of pulses at each ablation point also affects the actual volume of material removed. At the same single-pulse energy, using multiple pulses superimposed at the same location can increase the ablation depth, but may lead to a heat accumulation effect. Therefore, typically 1-5 pulses are used per ablation point, the specific number depending on the required single-point depth and the ablation rate of the material. For example, each microlens is formed by ablation of 15 concentric layers, and each ablation point in each layer typically uses only one pulse to ensure cold processing conditions.

[0038] The radius of curvature of the final microlens unit is controlled by adjusting the radius sequence of the concentric circles in each layer and the number of pulses at each ablation point. For example, to obtain a convex lens with a small radius of curvature, the ablation depth in the central region needs to be much greater than that in the edge region, which can be achieved by increasing the number of pulses or increasing the single pulse energy in the central region; to obtain a smooth lens with a large radius of curvature, the depth difference between layers is smaller. After adjusting the above parameters, a microlens unit with a preset radius of curvature and diameter is fabricated.

[0039] S205. According to the preset arrangement, the formation process of a single microlens unit is repeated at different positions on the processing surface to make several microlens units regularly arranged to obtain a microlens array.

[0040] After one microlens unit is processed, the diamond substrate is moved using a high-precision displacement stage to position the processing location at the center coordinates of the next microlens unit. Steps S201 to S204 are then repeated to form the second microlens unit. This process is repeated, arranging thousands of microlens units regularly across the entire processed surface according to a preset array arrangement and spacing between adjacent units. Once all units are processed, a complete microlens array is obtained. This array covers the entire processed surface of the diamond substrate, including the previously divided quadrant regions. Because each microlens unit is formed independently and the processing parameters are repeatable, the units in the array possess highly consistent optical performance.

[0041] In this embodiment, a processing method combining point-by-point ablation and concentric circle scanning is employed. This allows for precise control of the depth of each ablation point and the radius of curvature and diameter of the microlens units, thereby fabricating a microlens array conforming to a preset surface profile on the CVD diamond surface. This method utilizes the cold processing characteristics of femtosecond lasers to effectively suppress diamond graphitization and microcrack formation, ensuring the integrity of the diamond substrate. Furthermore, by adjusting the scanning radius of the concentric circles and the number of pulses at each ablation point, the radius of curvature of the microlenses can be controlled, forming a regular array in a hexagonal close-packed or square arrangement, thus constructing an optical curved substrate for the subsequent stacking of nanograting layers.

[0042] A grating scan is performed on the surface of the microlens array to form a nanograting layer on the surface of each microlens unit. Different linear polarization directions are used for grating scans in several quadrant regions. The grating scan of the microlens array surface is described in detail below; please refer to [link to relevant documentation]. Figure 3 , Figure 3 A schematic flowchart of an embodiment of the CVD diamond processing method provided in this application, which involves grating scanning of the surface of a microlens array, includes: S301. For each of the several quadrant regions, the linear polarization direction of the femtosecond laser is set to a preset angle, and the preset angles of the several quadrant regions are different from each other. After the microlens array is fabricated, the diamond matrix remains stationary. First, the linear polarization direction for each quadrant region is determined according to design requirements. To ensure that different regions exhibit different structural colors at the same viewing angle, the preset angles for each region should be distinct. When divided into four quadrants, the first quadrant can be set to 0°, the second quadrant to 45°, the third quadrant to 90°, and the fourth quadrant to 135°. Other angle combinations can also be used, such as 0°, 60°, 120°, 180°, etc., as long as they are different from each other.

[0043] The specific operation for setting the polarization direction is as follows: A half-wave plate or polarization rotator is set in the femtosecond laser optical path. The linear polarization direction of the output laser is changed by rotating the angle of the half-wave plate. The rotation angle of the half-wave plate is proportional to the change in the linear polarization direction. For example, rotating the half-wave plate by an angle θ results in a 2θ-angle rotation of the linear polarization direction. Therefore, to obtain 0° linear polarization, the half-wave plate is set to 0°; to obtain 45° linear polarization, the half-wave plate is rotated by 22.5°; to obtain 90° linear polarization, the half-wave plate is rotated by 45°; and to obtain 135° linear polarization, the half-wave plate is rotated by 67.5°. Before each quadrant switching process, the half-wave plate must be automatically rotated to the target angle and calibrated using a polarization measuring instrument to ensure that the angle deviation is less than ±1°.

[0044] S302. Under the set linear polarization direction, perform grating scanning on the surface of the microlens array so that a nano grating layer with corresponding grating orientation is formed on the surface of each microlens unit. After setting the polarization direction, the grating scanning program is initiated. The femtosecond laser beam moves back and forth along parallel lines, covering the entire microlens array surface within the current quadrant line by line. During scanning, the laser beam first starts from a corner of the current quadrant, rapidly scanning a straight line along the X direction while simultaneously activating laser pulse output; upon reaching the boundary, the laser is deactivated, and the stage moves one line spacing along the Y direction, then performs a second scan line in the opposite direction. This process is repeated until the entire quadrant area is covered. During the scanning process, the femtosecond laser interacts with the diamond surface, self-organizing to form a periodic nanograting layer. The period of this nanograting layer is determined by the laser wavelength and the diamond refractive index.

[0045] The process of forming nanograting layers with corresponding grating orientations on the surface of each microlens unit also includes: controlling the grating orientation of the nanograting layer by adjusting the linear polarization direction of the femtosecond laser, so that the grating orientation is perpendicular to the linear polarization direction. Specifically, the direction of the nanograting fringes induced by the femtosecond laser is always perpendicular to the linear polarization direction of the laser. Therefore, when the linear polarization direction is set to 0°, the direction of the formed nanograting fringes is 90°; when the linear polarization direction is 45°, the direction of the grating fringes is 135°; when the linear polarization direction is 90°, the direction of the grating fringes is 0°; and when the linear polarization direction is 135°, the direction of the grating fringes is 45°. Utilizing this rule, the orientation of the nanograting can be arbitrarily preset by selecting the linear polarization direction. Since the linear polarization directions of each quadrant are different, their corresponding grating orientations are also different, thus, at the same observation angle, different quadrant regions produce different diffraction colors due to the differences in grating orientation.

[0046] S303. Perform raster scanning on each region in several quadrant regions in sequence until all quadrant regions have been scanned.

[0047] To avoid cross-contamination or boundary interference between adjacent quadrants, each quadrant is typically processed sequentially in a clockwise or counterclockwise order. The specific operation is as follows: First, for the first quadrant, complete the raster scan of the entire first quadrant region according to the corresponding linear polarization direction; then move to the second quadrant, reset the linear polarization direction to the angle corresponding to the second quadrant, and perform the raster scan again; and so on, until all quadrants are completed. When scanning a particular quadrant, a mask can be used to block other quadrants, or the scanning area can be defined by controlling the start and end coordinates of the scan path to ensure clear boundaries and non-overlapping quadrant boundaries.

[0048] After all the scanning is completed, a nano-grating layer covers the microlens array on the diamond surface, and the grating orientation is different in each quadrant. When light shines on it, different quadrants will appear in different colors at the same viewing angle due to the difference in grating orientation; at the same time, due to the presence of the microlens array, each color point will also produce brightness flickering and continuous color gradation as the viewing angle changes, forming a multi-colored, dynamic and rich visual effect.

[0049] In this embodiment, a partitioned grating scanning method is used to scan the surface of the formed microlens array with different linear polarization directions for each quadrant region, resulting in a nanograting layer with different grating orientations on the surface of each microlens unit. Utilizing the physical principle that the fringe direction of the femtosecond laser-induced nanograting is perpendicular to the linear polarization direction, the grating orientation can be controlled simply by adjusting the half-wave plate angle, without needing to change the mask or other process parameters. This method is simple to operate and has good repeatability. Due to the different grating orientations, each quadrant region exhibits different structural colors at the same viewing angle, achieving a partitioned, multi-color visual effect.

[0050] This application also provides a CVD diamond, obtained using the processing method of any of the above embodiments. Please refer to... Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the microlens array in CVD diamond provided in this application. Figure 5 A schematic diagram of the microlens unit processing cross-section in CVD diamond provided in this application; the following is a detailed embodiment of CVD diamond: CVD diamond includes: a diamond matrix 401, a microlens array consisting of several regularly arranged microlens units 402, and a nanograting layer 403.

[0051] The microlens array is formed on the processed surface of the diamond substrate 401, and the microlens array is composed of several regularly arranged microlens units 402; the nanograting layer 403 is formed on the surface of each microlens unit 402.

[0052] The diameter of the microlens unit 402 is 5-100μm, the radius of curvature is 10-500μm, and the spacing between adjacent microlens units 402 is 0-20μm; the period of the nanograting layer 403 is 100-800nm, and the depth is 50-300nm.

[0053] The microlens array contains at least two microlens units 402 with different radii of curvature, and the microlens units 402 with different radii of curvature are arranged in a preset pattern.

[0054] In CVD diamond, the diamond matrix 401 is a single-crystal diamond with at least one machined facet. This facet is polished to a surface roughness of less than 2 nm, providing a flat substrate for the fabrication of the microlens array. The thickness of the diamond matrix 401 can be selected according to application requirements, for example, in the range of 0.3 mm to 2.0 mm.

[0055] The microlens array is formed on the machined surface of the diamond substrate 401 and consists of several regularly arranged microlens units 402. Each microlens unit 402 can be a convex or concave spherical or aspherical microlens, with a diameter controlled between 5 μm and 100 μm and a radius of curvature controlled between 10 μm and 500 μm. The spacing between adjacent microlens units 402 can be selected between 0 μm and 20 μm to adjust the density of the shimmering light spots. The arrangement of the microlens units 402 can be hexagonal close-packed or square. Hexagonal close-packed can achieve the highest unit density and produce a more continuous optical effect; square arrangement is convenient for matching with certain regular pattern designs. In a preferred embodiment, the microlens array can include at least two types of microlens units 402 with different radii of curvature. These microlens units 402 with different radii of curvature are arranged in a preset pattern partition, thereby forming a recognizable pattern effect on a macroscopic scale, such as brand logos, geometric shapes, or decorative textures. Microlens units 402 with different radii of curvature have different focal lengths and light-gathering capabilities, thus producing different flicker frequencies and brightness variations at different viewing angles, further enriching the visual effects.

[0056] A nanograting layer 403 is formed on the surface of each microlens unit 402, and is a laser-induced periodic surface structure formed by femtosecond laser grating scanning. This nanograting layer 403 is a periodic nanograting structure with a period between 100 nm and 800 nm and a depth between 50 nm and 300 nm. The grating direction of the nanograting layer 403 is perpendicular to the linear polarization direction of the femtosecond laser used in the processing. Therefore, by setting different linear polarization directions in different areas, nanogratings with different orientations can be obtained in different regions, resulting in different structural colors in different regions at the same observation angle. Without partitioning, the entire processed surface has a uniform grating orientation, exhibiting a single gradient color; with partitioning, a multi-color partitioning effect is achieved.

[0057] In this embodiment, the CVD diamond utilizes a microlens array and a nanograting layer 403 working together. When illuminated by external light, the microlens array generates alternating bright and dark shimmering spots through refraction and reflection, while the nanograting layer 403 causes the color of each shimmering spot to continuously change with the viewing angle through diffraction. When these two elements are superimposed, the observer can see each spot dynamically shimmering with flowing colors, creating an overall effect far superior to a single structure. Simultaneously, the high hardness, high thermal conductivity, and near-infrared transmittance of the diamond matrix 401 are fully preserved, allowing this CVD diamond to be used independently as a jewelry piece or as an optical window for smart wearable devices.

Claims

1. A method for processing CVD diamonds, characterized in that, The processing method includes: The surface of the diamond matrix is ​​polished until the surface roughness is less than 2nm, and the polished surface is divided into several quadrant regions. The processing surface is ablated point by point using a femtosecond laser to obtain a microlens array composed of several arranged microlens units; The surface of the microlens array is scanned by a grating to form a nanograting layer on the surface of each microlens unit; wherein, different linear polarization directions are used for grating scanning in the several quadrant regions. The processed diamond matrix is ​​ultrasonically cleaned to obtain a CVD diamond with a microlens array.

2. The processing method according to claim 1, characterized in that, The process of ablating the processed surface point by point with a femtosecond laser to obtain a microlens array composed of several arranged microlens units includes: The microlens unit is ablated point by point from the edge to the center using a concentric circle scanning method, and the depth of each ablation point is controlled within a preset range by controlling the single pulse energy of the femtosecond laser. By adjusting the scanning radius of the concentric circles and the number of pulses at each ablation point, the radius of curvature and diameter of the microlens unit are controlled within a preset range to obtain a single microlens unit. According to a preset arrangement, the formation process of the individual microlens unit is repeated at different positions on the processing surface, so that several microlens units are arranged regularly to obtain a microlens array.

3. The processing method according to claim 2, characterized in that, The method of ablation point by point along the edge of each microlens unit in the microlens array towards the center using a concentric circle scanning method, and controlling the depth of each ablation point within a preset range by controlling the single-pulse energy of the femtosecond laser, includes: The energy of a single pulse of a femtosecond laser is controlled so that each laser pulse forms an ablation point of a preset depth on the processing surface; The single pulse energy is adjusted according to the correspondence between the single pulse energy and the depth of the ablation point, so that the actual depth of each ablation point falls within the target depth range. Each ablation point distributed along the concentric circle trajectory is given a corresponding single pulse energy, so that each ablation point distributed along the concentric circle trajectory has the same depth, or the depth of each ablation point varies in a stepwise manner with the radius of the concentric circle.

4. The processing method according to claim 1, characterized in that, The step of performing grating scanning on the surface of the microlens array to form a nanograting layer on the surface of each microlens unit, wherein grating scanning is performed using different linear polarization directions in the plurality of quadrant regions, includes: For each of the plurality of quadrant regions, the linear polarization direction of the femtosecond laser is set to a preset angle, and the preset angles of the plurality of quadrant regions are different from each other; Under the set linear polarization direction, the surface of the microlens array is scanned by a grating, so that a nano-grating layer with a corresponding grating orientation is formed on the surface of each microlens unit. Raster scanning is performed sequentially on each of the aforementioned quadrant regions until all quadrant regions have been scanned.

5. The processing method according to claim 4, characterized in that, The formation of nanograting layers with corresponding grating orientations on the surface of each of the microlens units further includes: By adjusting the linear polarization direction of the femtosecond laser, the grating orientation of the nanograting layer is controlled so that the grating orientation is perpendicular to the linear polarization direction.

6. The processing method according to claim 1, characterized in that, The step of dividing the polished surface into several quadrant regions includes: marking cross-shaped dividing lines on the polished surface to divide the surface into four quadrant regions of equal area.

7. A CVD diamond with a microlens array, characterized in that, It is prepared by the processing method according to any one of claims 1 to 6.

8. The CVD diamond according to claim 7, characterized in that, The CVD diamond comprises: a diamond matrix, a microlens array, and a nanograting layer; The microlens array is formed on the machined surface of the diamond matrix, and the microlens array is composed of a number of regularly arranged microlens units; The nanograting layer is formed on the surface of each of the microlens units.

9. The CVD diamond according to claim 8, characterized in that, The diameter of the microlens unit is 5-100μm, the radius of curvature is 10-500μm, and the spacing between adjacent microlens units is 0-20μm; The period of the nanograting layer is 100-800nm, and the depth is 50-300nm.

10. The CVD diamond according to claim 8, characterized in that, The microlens array contains at least two types of microlens units with different radii of curvature, and the microlens units with different radii of curvature are arranged in a preset pattern.

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