A device and processing method for laser-prepared surface inverted trapezoidal grooves

Abstract

The present invention discloses a device and method for laser-fabricating inverted trapezoidal grooves on a surface. The device comprises a brushless motor, a rotating prism, a reflector assembly, a focusing mirror, a rotating stage, a Z-axis lifting stage, and an XY movable stage. The XY movable stage is mounted on a base, the Z-axis lifting stage is mounted on the XY movable stage, and the rotating stage is mounted on the Z-axis lifting stage. The rotating prism is connected to the output shaft of the brushless motor. The rotating prism is used to continuously change the incident angle of the laser beam. The reflector assembly is used to guide and adjust the propagation direction of the laser beam. The focusing mirror is used to focus the laser beam adjusted by the reflector assembly onto the sample surface. The present invention can improve the processing quality of the grooves and improve the liquid transport performance.

Description

Technical Field

[0001] The present invention relates to the technical field of laser processing, in particular to a device and a processing method for preparing surface inverted trapezoidal grooves by laser. Background Art

[0002] In fields such as microfluidic chips, fuel cell flow channels, and aerospace condensation surfaces, the geometric characteristics of surface microgrooves have a crucial influence on the directional liquid transport performance. Conventional laser direct writing techniques, such as nanosecond or femtosecond laser processing, are typically used to create rectangular or V-shaped grooves. However, due to the uniformity of the cross-section, these structures have limited capillary force enhancement, resulting in liquid transport speeds generally below 5 mm / s, making them difficult to meet the requirements of high-precision and high-efficiency liquid manipulation. Research has shown that trapezoidal or inverted-tapered grooves, which are narrow at the top and wide at the bottom, can significantly increase liquid velocity through a gradient capillary pressure differential. For example, at the same depth, the liquid transport speed of trapezoidal grooves can be increased to over 15 mm / s. However, the fabrication of such structures faces significant challenges. Conventional laser processing systems lack the ability to dynamically control the laser incident angle, making it difficult to achieve continuous angle adjustment within a ±60° range in a single process. This makes it difficult to form structures with gradually varying groove widths. Furthermore, when processing grooves with high aspect ratios (greater than 5:1), laser heat accumulation can easily lead to deteriorated sidewall roughness (Ra > 2 μm), affecting the wettability and stability of the functional surface. In addition, the inclination error of the groove wall must be strictly controlled within 0.5°, and the bottom width fluctuation must be less than 3%, which places extremely high demands on the motion synchronization and optical accuracy of the processing system.

[0003] In existing technologies, although multi-beam interferometry can generate gradient structures, its processing flexibility and efficiency are low (less than 1mm² / s), and it is difficult to achieve continuous processing of complex paths. Mechanical tool engraving is limited by the problem of dimensional drift caused by tool wear and cannot meet the requirements of micron-level precision. For example, the contact friction between the tool and the material during mechanical engraving can cause thermal deformation, resulting in groove depth consistency deviation exceeding ±5%, seriously affecting the uniformity of capillary force distribution. These limitations make the large-scale preparation of high-performance gradient grooves an industry problem, especially in fields such as biomedical organ chips and fuel cell bipolar plate flow channels, which have strict requirements on microstructure accuracy and reliability. Existing technologies have difficulty breaking through the bottleneck of balancing efficiency and quality. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a device and processing method for laser preparation of surface inverted trapezoidal grooves that can improve the processing quality of the grooves and the liquid transport performance.

[0005] The present invention is achieved through the following technical solutions: A device for laser preparation of inverted trapezoidal grooves on a surface, comprising a brushless motor, a rotating prism, a reflector group, a focusing mirror, a rotating table, a Z-axis lifting table, and an XY movable table, wherein the XY movable table is arranged on a base, the Z-axis lifting table is arranged on the XY movable table, the rotating table is arranged on the Z-axis lifting table, the rotating prism is connected to the output shaft of the brushless motor, the rotating prism is used to achieve continuous change of the incident angle of the laser beam, the reflector group is used to guide and adjust the propagation direction of the laser beam, and the focusing mirror is used to focus the laser beam adjusted by the reflector group onto the sample surface.

[0006] Furthermore: the reflector group is composed of at least two reflectors, each of which has a size of 20 mm×20 mm and a reflectivity greater than 99.9%.

[0007] Furthermore: the reflector group consists of a first reflector, a second reflector, and a third reflector, the first reflector and the second reflector are located on the same vertical axis, the second reflector and the third reflector are located on the same horizontal axis, the rotating prism is located between the second reflector and the third reflector, and the third reflector and the focusing mirror are located on the same vertical axis.

[0008] Furthermore: the focal length range of the focusing mirror is 50mm to 200mm, the adjustable range is ±10mm, and the spot diameter range is 1um to 100um.

[0009] Furthermore, the rotating prism is made of high-refractive-index optical glass with a precisely polished surface, the rotating precision of the rotating prism is higher than 0.01°, and the adjustable speed range of the rotating prism is 0-10 4 rpm.

[0010] Furthermore: the rotation range of the rotating table is 0° to 360°, and the rotation accuracy is ±0.05°.

[0011] Furthermore: the travel range of the Z-axis lifting platform is 0mm to 50mm, and the displacement accuracy is ±1um.

[0012] A laser processing method for preparing surface inverted trapezoidal grooves includes the following steps:

[0013] S1. Fix the sample on a rotating stage and adjust the sample height using the Z-axis lift to ensure that the sample surface precisely matches the focal plane of the focusing lens.

[0014] S2. Set the speed parameters of the brushless motor and the translation speed parameters of the XY moving stage. At the same time, adjust the positions of the reflector group and the focusing mirror;

[0015] S3. Start the brushless motor and XY motion platform. The brushless motor drives the rotating prism according to the set speed parameters, and the XY motion platform drives the sample in the horizontal direction according to the set translation speed parameters. The height of the Z-axis lift is adjusted as needed to position the sample in three dimensions. After the laser beam is guided by the reflector group and focused by the focusing lens, it acts on the sample surface at a dynamically changing incident angle to process a trapezoidal cross-section groove on the sample. During the trapezoidal cross-section groove processing process, the laser parameters are monitored and adjusted in real time.

[0016] S4. After completing the predetermined processing path, stop processing and remove the sample for cleaning and drying.

[0017] Furthermore, when the laser beam in step S3 acts on the sample surface at a dynamically changing incident angle, the incident angle of the laser beam changes continuously within a range of ±60°.

[0018] Furthermore: the rotation speed parameter of step S2 is 5000 rpm, and the translation speed parameter of the XY moving platform is 10 mm / s.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The brushless motor drives the rotating prism to rotate at high speed, so that the incident angle of the laser beam can be continuously changed within the range of ±60°. At the same time, the XY movable stage translates in the horizontal direction, the Z-axis lifting stage moves in the vertical direction, and the rotary stage drives the sample to rotate, thereby processing a precisely proportioned inverted trapezoidal groove on the sample. The laser incident angle and the movement speed of the XY movable stage and Z-axis lifting stage can be precisely controlled to ensure the precise ratio of the top and bottom widths of the groove and the consistency of the groove depth, thereby improving the groove processing quality and liquid transport performance.

[0021] 2. The rated power range of the brushless motor is 500W to 1000W, which can provide stable torque output to ensure the stability of the rotating prism at high speed. The rotating prism is installed on the output shaft of the brushless motor. The brushless motor drives the rotating prism to rotate at high speed, so that the incident angle of the laser beam changes continuously. Its speed can be adjusted between 0-10 4 The rpm range is precisely adjusted to meet different processing requirements, ensuring that the laser beam can be incident on the sample surface at a precise angle. The rotating prism is made of high-refractive-index optical glass, and the surface is precisely polished to ensure the reflection and refraction effect of the laser beam. The rotation accuracy of the rotating prism is higher than 0.01°, ensuring precise control of the laser beam incident angle.

[0022] 3. The reflector group consists of two or more reflectors. The size of each reflector is 20mm×20mm, and the reflectivity is greater than 99.9%, which can ensure the efficient transmission of the laser beam.

[0023] 4. By controlling the focal length and spot size of the focusing mirror, the laser energy is ensured to be concentrated and evenly applied to the sample surface, achieving efficient and precise material removal and structure forming. The focal length of the focusing mirror ranges from 50mm to 200mm, with an adjustable range of ±10mm, and the spot diameter ranges from 1μm to 100μm, which can meet processing tasks with different size and precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a device for laser-fabricating inverted trapezoidal grooves on a surface according to the present invention;

[0025] Figure 2 Schematic diagram of the laser light path of the device for laser-forming inverted trapezoidal grooves on a surface according to the present invention;

[0026] Figure 3 A schematic structural diagram of a rotating prism in a device for laser-forming inverted trapezoidal grooves on a surface according to the present invention;

[0027] Figure 4 Schematic diagram of the inverted trapezoidal groove processed by the present invention;

[0028] Figure 5 This is a capillary climbing effect diagram of the inverted trapezoidal groove processed by the present invention.

[0029] Explanation of the accompanying drawings: 1-brushless motor, 2-rotating prism, 3-reflector group, 4-focusing mirror, 5-rotating stage, 6-Z-axis lifting stage, 7-XY moving stage, 8-base, 9-first reflector, 10-second reflector, 11-third reflector, 12-coupling, 13-sample, 14-inverted trapezoidal groove. DETAILED DESCRIPTION

[0030] A device for laser preparation of inverted trapezoidal grooves on a surface includes a brushless motor 1, a rotating prism 2, a reflector group 3, a focusing mirror 4, a rotating table 5, a Z-axis lifting table 6, and an XY movable table 7. The XY movable table 7 is arranged on a base 8, the Z-axis lifting table 6 is arranged on the XY movable table 7, and the rotating table 5 is arranged on the Z-axis lifting table 6. The rotating prism 2 is connected to the output shaft of the brushless motor 1. The rotating prism 2 is used to achieve continuous change of the incident angle of the laser beam. The reflector group 3 is used to guide and adjust the propagation direction of the laser beam. The focusing mirror is used to focus the laser beam adjusted by the reflector group 3 onto the surface of the sample 13.

[0031] The reflector group 3 is composed of at least two reflectors, each of which has a size of 20 mm×20 mm and a reflectivity greater than 99.9%.

[0032] The reflector group 3 is composed of a first reflector 9, a second reflector 10, and a third reflector 11. The first reflector 9 and the second reflector 10 are located on the same vertical axis, the second reflector 10 and the third reflector 11 are located on the same horizontal axis, the rotating prism 2 is located between the second reflector 10 and the third reflector 11, and the third reflector 11 and the focusing mirror 4 are located on the same vertical axis.

[0033] The focal length range of the focusing lens 4 is 50 mm to 200 mm, the adjustable range is ±10 mm, and the spot diameter range is 1 μm to 100 μm.

[0034] The rotating prism 2 is made of high-refractive-index optical glass with a precision-polished surface. The rotating precision of the rotating prism 2 is higher than 0.01°, and the adjustable speed range of the rotating prism 2 is 0-10 4 rpm.

[0035] The brushless motor 1 is connected to the rotating prism 2 via a coupling 12. The rated power of the brushless motor 1 ranges from 500W to 1000W.

[0036] The rotation range of the rotating stage 5 is 0° to 360°, and the rotation accuracy is ±0.05°.

[0037] The travel range of the Z-axis lifting platform 6 is 0 mm to 50 mm, and the displacement accuracy is ±1 μm.

[0038] The travel range of the XY moving stage 7 is 0mm to 300mm on the X axis and 0mm to 200mm on the Y axis, and the displacement accuracy is ±2um.

[0039] The preferred embodiments of the processing method of the present invention are described below.

[0040] In this embodiment, a metal sheet with a size of 60 mm×60 mm×0.3 mm is selected as the sample. The sample has good thermal conductivity and mechanical stability and is suitable for the application scenario of the microfluidic chip.

[0041] A laser processing method for preparing surface inverted trapezoidal grooves includes the following steps:

[0042] S1. Fix the sample on a rotating stage and adjust the sample height using the Z-axis lift to ensure that the sample surface precisely matches the focal plane of the focusing lens.

[0043] S2. Set the speed parameters of the brushless motor and the translation speed parameters of the XY moving platform. At the same time, adjust the positions of the reflector group and the focusing mirror.

[0044] S3. Start the brushless motor and XY moving platform. The brushless motor drives the rotating prism to rotate according to the set speed parameters. The XY moving platform drives the sample to translate horizontally according to the set translation speed parameters. Adjust the height of the Z-axis lifting platform as needed to position the sample in three dimensions. After the laser beam is guided by the reflector group and focused by the focusing mirror, it acts on the sample surface with a dynamically changing incident angle to process trapezoidal cross-section grooves on the sample. During the trapezoidal cross-section groove processing process, the laser parameters are monitored and adjusted in real time.

[0045] S4. After completing the predetermined processing path, stop processing and remove the sample for cleaning and drying.

[0046] The rotation speed parameter in step S2 is 5000 rpm. This speed enables the rotating prism to rotate at an appropriate speed, achieving continuous variation in the laser beam incident angle during the processing process, meeting the forming requirements of the inverted trapezoidal groove. At the same time, the translation speed parameter of the XY mobile stage is set to 10 mm / s. The movement speed of the XY mobile stage matches the speed of the brushless motor, ensuring microsecond-level synchronization control of the laser beam incident angle and sample movement, achieving precise forming of the inverted trapezoidal groove. The laser power is set to 30 W, the pulse width is 10 ps, ​​the frequency is 1 MHz, and the spot diameter is 30 μm, thereby balancing processing efficiency and processing accuracy while avoiding excessive thermal damage.

[0047] In terms of optical path adjustment, the positions of the reflector group and the focusing mirror are adjusted to ensure that the laser beam can be accurately guided by the reflector group and focused on the sample surface by the focusing mirror. Through optical path adjustment, the spot diameter is stabilized at about 15um, achieving high-precision laser processing.

[0048] When the laser beam in step S3 acts on the sample surface at a dynamically changing incident angle, the incident angle of the laser beam continuously changes within a range of ±60°.

[0049] The processed samples were applied to microfluidic chips to test their liquid transport performance. The test results showed that the sample performed well in liquid transport, with significantly enhanced capillary force and significantly increased liquid transport speed. Compared with samples prepared by traditional methods, its liquid transport efficiency increased by about 30%. The capillary climbing effect of the processed trapezoidal groove is shown in the figure below. Figure 5 This fully verifies the superior performance of the processing system of the present invention.

[0050] Comparative Example

[0051] In this comparative example, a metal sheet with a size of 60mm×60mm×0.3mm is selected as the sample, fixed on a rotating table, and the sample height is adjusted by the Z-axis lifting table so that the sample surface is accurately matched with the focal plane of the focusing mirror. The brushless motor speed is set to 5000rpm, the XY moving stage translation speed is 10mm / s, the laser power is 30W, the pulse width is 10ps, the frequency is 1MHz, and the spot diameter is 30μm. These parameters are consistent with the embodiments of the present invention. Adjust the position of the reflector group and the focusing mirror to ensure that the laser beam can be accurately focused on the sample surface to form a spot diameter of about 15μm. Unlike the embodiments of the present invention, in this comparative example, a fixed incident angle is used for processing rather than a dynamically changing incident angle. After starting the brushless motor and the XY moving stage, the laser beam is guided by the reflector group and focused by the focusing mirror, and then acts on the sample surface at a fixed incident angle to start processing the trapezoidal cross-section groove. During the processing, the laser parameters are monitored and adjusted in real time to ensure processing accuracy and quality. At the same time, heat accumulation is suppressed by the thermal management system to avoid the deterioration of the side wall roughness. After the processing is completed, the sample is cleaned and dried. The processed sample is applied to the microfluidic chip to test its liquid transport performance. The test results show that the sample does not perform as well as the embodiment of the present invention in terms of liquid transport. The capillary force is improved, but not as significant as the embodiment of the present invention, and the liquid transport speed is significantly reduced compared with the embodiment of the present invention. This is mainly due to the fact that the geometric shape of the trapezoidal cross-section groove caused by the fixed incident angle processing is not optimized enough, which affects the liquid transport efficiency.

[0052] The above detailed description is a specific description of a feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not depart from the present invention should be included in the patent scope of this case.

Claims

1. A device for laser-forming inverted trapezoidal grooves on a surface, characterized in that: The brushless machine comprises a brushless motor, a rotating prism, a reflector assembly, a focusing mirror, a rotating stage, a Z-axis lifting stage, and an XY movable stage. The XY movable stage is disposed on a base, the Z-axis lifting stage is disposed on the XY movable stage, and the rotating stage is disposed on the Z-axis lifting stage. The rotating prism is connected to the output shaft of the brushless motor. The rotating prism is used to continuously change the incident angle of the laser beam. The reflector assembly is used to guide and adjust the propagation direction of the laser beam. The focusing mirror is used to focus the laser beam adjusted by the reflector assembly onto the sample surface. The reflector group consists of at least two reflectors, each of which has a size of 20 mm × 20 mm and a reflectivity greater than 99.9%; The reflector group consists of a first reflector, a second reflector, and a third reflector, the first reflector and the second reflector are located on the same vertical axis, the second reflector and the third reflector are located on the same horizontal axis, the rotating prism is located between the second reflector and the third reflector, and the third reflector and the focusing mirror are located on the same vertical axis; The focal length range of the focusing mirror is 50mm to 200mm, the adjustable range is ±10mm, and the spot diameter range is 1μm to 100μm; The material of the rotating prism is high refractive index optical glass with a precision polished surface. The rotation accuracy of the rotating prism is higher than 0.01°. The adjustable speed range of the rotating prism is 0-10 4 rpm.

2. The device for laser forming inverted trapezoidal grooves on a surface according to claim 1, characterized in that: The rotation range of the rotating stage is 0° to 360°, and the rotation accuracy is ±0.05°.

3. The device for laser forming inverted trapezoidal grooves on a surface according to claim 2, characterized in that: The travel range of the Z-axis lifting platform is 0mm to 50mm, and the displacement accuracy is ±1μm.

4. A laser processing method for forming inverted trapezoidal grooves on a surface, characterized in that: The device for laser-fabricating surface inverted trapezoidal grooves according to claim 1 comprises the following specific steps: S1. Fix the sample on a rotating stage and adjust the sample height using the Z-axis lift to ensure that the sample surface precisely matches the focal plane of the focusing lens. S2. Set the speed parameters of the brushless motor and the translation speed parameters of the XY moving stage. At the same time, adjust the positions of the reflector group and the focusing mirror; S3. Start the brushless motor and XY motion platform. The brushless motor drives the rotating prism according to the set speed parameters, and the XY motion platform drives the sample in the horizontal direction according to the set translation speed parameters. The height of the Z-axis lift is adjusted as needed to position the sample in three dimensions. After the laser beam is guided by the reflector group and focused by the focusing lens, it acts on the sample surface at a dynamically changing incident angle to process a trapezoidal cross-section groove on the sample. During the trapezoidal cross-section groove processing process, the laser parameters are monitored and adjusted in real time. S4. After completing the predetermined processing path, stop processing and remove the sample for cleaning and drying.

5. The laser processing method for forming inverted trapezoidal grooves on a surface according to claim 4, characterized in that: When the laser beam in step S3 acts on the sample surface at a dynamically changing incident angle, the incident angle of the laser beam continuously changes within a range of ±60°.

6. The laser processing method for forming inverted trapezoidal grooves on a surface according to claim 4, characterized in that: In step S2, the rotation speed parameter is 5000 rpm, and the translation speed parameter of the XY moving platform is 10 mm / s.

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