Reflective Bessel laser micro / nano fabrication device and method

Abstract

This invention provides a reflective Bessel laser micro / nano processing apparatus and method, relating to the field of laser micro / nano processing technology. The reflective Bessel laser micro / nano processing apparatus includes a light source assembly, a reflective Bessel assembly, a beam focusing assembly, and a control assembly. The light source assembly is adapted to emit a laser beam; the reflective Bessel assembly is adapted to shape the laser beam into a Bessel beam and change the propagation direction of the Bessel beam to form a reflective Bessel beam; the beam focusing assembly is adapted to converge the reflective Bessel beam; and the control assembly is adapted to control the relative position between the focal point of the reflective Bessel beam and the workpiece. Using the reflective Bessel laser micro / nano processing apparatus and method provided by this invention, high-precision processing of workpieces can be achieved, improving the yield rate.

Description

Technical Field

[0001] This invention relates to the field of laser micro-nano processing technology, and in particular to a reflective Bessel laser micro-nano processing device and method. Background Technology

[0002] Compared to traditional machining, laser processing has unique and superior performance characteristics. As a non-contact processing method, laser processing does not involve tool wear or cutting force on the workpiece, thus preventing workpiece deformation. It can also process workpieces made of different materials. The laser beam is easy to guide and focus to achieve directional changes, making it easy to integrate with CNC systems and achieving high processing accuracy.

[0003] In applications such as radar, electronic warfare, and communications, the performance requirements for equipment and its core functional components are becoming increasingly stringent, which in turn necessitates higher machining precision when processing these components. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the background art. To this end, the present invention provides a reflective Bessel laser micro / nano processing device and method, which can achieve high-precision processing of workpieces and improve the yield rate. The specific technical solution is as follows:

[0005] A first aspect of the present invention provides a reflective Bessel laser micro / nano fabrication device, comprising:

[0006] A light source assembly adapted to emit a laser beam;

[0007] A reflective Bessel assembly, the reflective Bessel assembly being adapted to shape the laser beam into a Bessel beam and change the propagation direction of the Bessel beam to form a reflective Bessel beam;

[0008] A beam focusing assembly adapted to converge the reflective Bessel beam;

[0009] A control component adapted to control the relative position between the focal point of the reflective Bessel beam and the workpiece.

[0010] According to one embodiment of the present invention, the light source assembly includes a laser and a transmission optical path, the laser being adapted to emit the laser beam and the transmission optical path being adapted to transmit the laser beam.

[0011] According to one embodiment of the present invention, the transmission optical path includes a first reflector adapted to transmit the laser beam to a first focal point.

[0012] According to one embodiment of the present invention, the reflective Bessel assembly includes a beam expander, a reflective axonoid mirror, and a second reflector group. The beam expander is adapted to change the diameter of the laser beam at the first focal point, the reflective axonoid mirror is adapted to convert the laser beam passing through the beam expander into the Bessel beam, and the second reflector group is adapted to change the propagation direction of the Bessel beam to form the reflective Bessel beam and converge the reflective Bessel beam to the second focal point.

[0013] According to one embodiment of the present invention, the beam focusing assembly includes a microscope objective adapted to receive a reflected Bessel beam at a second focal point and focus the reflected Bessel beam to a third focal point.

[0014] According to one embodiment of the present invention, the control component includes a galvanometer adapted to change the position of the third focal point of the reflective Bessel beam.

[0015] A second aspect of the present invention provides a method for reflective Bessel laser micro / nano fabrication based on the reflective Bessel laser micro / nano fabrication device described above, comprising:

[0016] Emit the laser beam;

[0017] Expand the laser beam;

[0018] The expanded laser beam is converted into the Bessel beam;

[0019] The propagation direction of the Bessel beam is changed to form the reflective Bessel beam, and the reflective Bessel beam is brought into the beam focusing assembly;

[0020] The reflective Bessel beam is focused onto the workpiece;

[0021] Adjust the positional relationship between the focal point of the reflective Bessel beam and the workpiece.

[0022] According to an embodiment of the present invention, the step of expanding the laser beam includes:

[0023] The laser beam is continuously expanded by varying its magnification, with a beam expansion ratio of 2:1 to 6:1.

[0024] According to one embodiment of the present invention, the step of changing the propagation direction of the Bessel beam to form the reflective Bessel beam and causing the reflective Bessel beam to enter the beam focusing assembly includes:

[0025] The Bessel beam is passed through a second set of mirrors to change its propagation direction and form a reflective Bessel beam, which is then focused by a microscope objective.

[0026] According to an embodiment of the present invention, the step of adjusting the positional relationship between the focal point of the reflective Bessel beam and the workpiece includes:

[0027] The positional relationship between the focal point of the reflective Bessel beam and the workpiece is adjusted by using a galvanometer.

[0028] The reflective Bessel laser micro / nano processing apparatus and method provided by embodiments of the present invention converts a laser beam into a reflective Bessel beam, thereby enabling high-precision machining of a workpiece. Specifically, the light source component in the reflective Bessel laser micro / nano processing apparatus emits a laser beam, which is then converted into a reflective Bessel beam after passing through the reflective Bessel component. The reflective Bessel beam is then focused onto the workpiece by a beam focusing component, and the workpiece is then processed. Compared to a transmissive Bessel beam, a reflective Bessel beam has lower energy loss, a reflectivity greater than 99%, and can achieve dispersion-free operation and maintain the pulse duration of ultrafast lasers. It also offers advantages such as no focus shift and a higher aspect ratio. Therefore, compared to machining with a transmissive Bessel beam, machining with a reflective Bessel beam can achieve higher precision and improve the yield of machined workpieces. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the reflective Bessel laser micro / nano processing device provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic flowchart of the reflective Bessel laser micro / nano fabrication method provided in an embodiment of the present invention.

[0032] Figure label:

[0033] 10. Light source assembly; 11. Laser; 12. Optical transmission path;

[0034] 21. Beam expander; 22. Reflective axial pyramid mirror; 23. Second reflecting mirror group;

[0035] 31. Microscope objective;

[0036] 41. Galvanometer;

[0037] 50. Workpiece. Detailed Implementation

[0038] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0039] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0041] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0043] like Figure 1 As shown, a first aspect embodiment of the present invention provides a reflective Bessel laser micro / nano processing device, including a light source assembly 10, a reflective Bessel assembly, a beam focusing assembly, and a control assembly. The light source assembly 10 is adapted to emit a laser beam. The reflective Bessel assembly is adapted to shape the laser beam into a Bessel beam and change the propagation direction of the Bessel beam to form a reflective Bessel beam. The beam focusing assembly is adapted to converge the reflective Bessel beam. The control assembly is adapted to control the relative position between the focal point of the reflective Bessel beam and the workpiece 50.

[0044] A transmissive Bessel beam is a special type of non-diffractive beam. Compared to a single-mode Gaussian beam, it has a large depth of focus. When a transmissive Bessel beam is focused by an external lens, it forms an elongated focusing region with the same diffraction-limited spot size as the lens, but it may also be many times the Rayleigh range.

[0045] Reflective Bessel beams are typically generated by reflective axial pyramidal mirrors. Compared to transmissive Bessel beams, they have lower energy loss, a reflectivity greater than 99%, and can achieve dispersion-free operation while maintaining the pulse duration of ultrafast lasers. They also offer advantages such as no focus shift and a higher aspect ratio. After being focused by a second set of 23 reflecting mirrors, the reflective Bessel beam can form a spot of ideal size and increase the laser power per unit area, enabling direct writing etching of workpiece 50 to meet processing accuracy requirements.

[0046] like Figure 1 As shown, in an embodiment of the present invention, the light source assembly 10 includes a laser 11 and a transmission optical path 12. The laser 11 is adapted to emit a laser beam, and the transmission optical path 12 is adapted to transmit the laser beam. The laser 11 is an ultrafast laser 11, and its pulse width should be on the order of femtoseconds, used to emit a laser beam.

[0047] Specifically, in this embodiment of the invention, the parameters of the ultrafast laser 11 are: wavelength 1064nm, single pulse energy 40μJ, and repetition frequency 2MHz.

[0048] In an embodiment of the present invention, the transmission optical path 12 includes a first reflector adapted to transmit a laser beam to a first focal point. The first reflector is located on the propagation path of the laser beam and is used to reflect the laser beam to a reflective Bezier component, wherein the first focal point is the laser incident point on the reflective Bezier component.

[0049] Specifically, in this embodiment of the invention, the first reflector is an ultrafast laser reflector with a suitable wavelength of 1064nm, a reflectivity greater than 99%, and a damage threshold greater than 0.4J / cm2.

[0050] like Figure 1 As shown, in an embodiment of the present invention, the reflective Bessel assembly includes a beam expander 21, a reflective axonoid mirror 22, and a second set of reflectors 23. The beam expander 21 is adapted to change the diameter of the laser beam at the first focal point. The reflective axonoid mirror 22 is adapted to convert the laser beam passing through the beam expander 21 into a Bessel beam. The second set of reflectors 23 is adapted to change the propagation direction of the Bessel beam to form a reflective Bessel beam and converge the reflective Bessel beam to the second focal point. The beam expander 21 can change the diameter of the laser beam so that the diameter of the laser beam is adapted to the subsequent optical devices such as the reflective axonoid mirror 22 and the second set of reflectors 23. After passing through the beam expander 21, the laser beam enters the reflective axial pyramid mirror 22. The reflective axial pyramid mirror 22 is also known as a diffraction pyramid or cone mirror in the optical industry. It is an optical element that converts the laser beam into a Bessel beam. Therefore, after passing through the reflective axial pyramid mirror 22, the laser beam is converted into a Bessel beam and enters the second set of mirrors 23. The second set of mirrors 23 can change the propagation direction of the Bessel beam to form a reflective Bessel beam and focus it onto the second focal point position on the microscope objective 31.

[0051] Specifically, in this embodiment of the invention, the beam expander 21 is a continuously variable adjustable beam expander with a beam expansion ratio adjustable from 2:1 to 6:1, the reflective axial pyramidal mirror 22 has an angle of 0.25 degrees, the incident light spot is 5 mm, and the outgoing Bessel beam has a diameter of 43 μm.

[0052] like Figure 1 As shown, in an embodiment of the present invention, the beam focusing assembly includes a microscope objective 31, which is adapted to receive a reflected Bessel beam at a second focal point and focus the reflected Bessel beam to a third focal point. The microscope objective 31 is used to converge the reflected Bessel beam to an ideal spot diameter, and the third focal point is a point in the processing area on the workpiece 50.

[0053] Specifically, in this embodiment of the invention, the selected microscope objective 31 has a magnification of 40x and a numerical aperture value of 0.65. Numerical aperture is one of the important parameters of the microscope objective 31. Numerical aperture is the product of the refractive index of the medium between the front lens of the objective and the object under examination and the sine of half the aperture angle.

[0054] like Figure 1 As shown, in this embodiment of the invention, the control component includes a galvanometer 41, which is adapted to change the position of the third focal point of the reflective Bezier beam. The galvanometer 41 can be used to change the position of the third focal point and to achieve patterned laser engraving through programming. By adjusting the third focal point of the reflective Bezier beam using the galvanometer 41, the processing focal point of the reflective Bezier beam can be applied to the workpiece 50 more precisely, improving processing accuracy.

[0055] Specifically, the galvanometer 41 system is selected as a 2D galvanometer system.

[0056] like Figure 2 As shown, an embodiment of the second aspect of the present invention provides a reflective Bessel laser micro / nano fabrication method, based on the reflective Bessel laser micro / nano fabrication apparatus in any of the above embodiments, the method comprising:

[0057] S100, emits a laser beam.

[0058] S200, expands the laser beam.

[0059] S300 converts the expanded laser beam into a Bessel beam.

[0060] S400: Change the propagation direction of the Bessel beam to form a reflective Bessel beam, and allow the reflective Bessel beam to enter the beam focusing assembly.

[0061] S500, Focus the reflective Bessel beam onto the workpiece 50.

[0062] S600, Adjust the positional relationship between the focal point of the reflective Bessel beam and the workpiece 50.

[0063] Specifically, the process of the reflective Bessel laser micro / nano fabrication method can be summarized as follows: The laser beam emitted by the light source assembly 10 is introduced into the beam expander 21 in the reflective Bessel assembly for beam expansion. The expanded laser beam then passes through the reflective axonal pyramidal mirror 22, thereby changing the energy distribution of the laser beam from a Gaussian distribution to a Bessel distribution. The Bessel beam, shaped into a Bessel distribution, passes through the second set of reflectors 23 to form a reflective Bessel beam. After passing through the microscope objective 31, a spot of ideal size is formed, and the laser power per unit area is increased before focusing onto the workpiece 50. By adjusting the positional parameters such as the relative distance and angular relationship between the workpiece 50 and the focal point through the control assembly, the reflective Bessel beam can perform direct writing etching on the workpiece 50, meeting the processing accuracy requirements. The etched pattern can be obtained through programming.

[0064] In an embodiment of the present invention, the step of expanding the laser beam includes:

[0065] The laser beam is continuously expanded by varying its magnification, with a beam expansion ratio of 2:1 to 6:1.

[0066] Among them, the beam expander 21 is a continuously variable adjustable beam expander with a beam expansion ratio adjustable from 2:1 to 6:1.

[0067] In an embodiment of the present invention, the step of changing the propagation direction of the Bessel beam to form a reflective Bessel beam and causing the reflective Bessel beam to enter the beam focusing assembly includes:

[0068] The Bessel beam is passed through the second set of mirrors 23 to change its propagation direction and form a reflected Bessel beam. The reflected Bessel beam is then focused by the microscope objective 31.

[0069] The selected microscope objective 31 has a magnification of 40x and a numerical aperture of 0.65.

[0070] In an embodiment of the present invention, the step of adjusting the positional relationship between the focal point of the reflective Bessel beam and the workpiece 50 includes:

[0071] The positional relationship between the focal point of the reflective Bessel beam and the workpiece 50 is adjusted by the galvanometer 41.

[0072] Among them, the galvanometer 41 is selected as a 2D galvanometer system.

[0073] In summary, the reflective Bessel laser micro / nano processing apparatus and method provided by the embodiments of the present invention converts a laser beam into a reflective Bessel beam, thereby enabling high-precision processing of the workpiece 50. Specifically, the light source component 10 in the reflective Bessel laser micro / nano processing apparatus emits a laser beam, which is converted into a reflective Bessel beam after passing through the reflective Bessel component. The reflective Bessel beam is then focused onto the workpiece 50 by the beam focusing component, and the workpiece 50 is processed. Compared with the transmission Bessel beam, the reflective Bessel beam has lower energy loss, a reflectivity greater than 99%, and can achieve dispersion-free operation and maintain the pulse duration of ultrafast lasers. It also has the advantages of no focus shift and a higher aspect ratio. Therefore, compared with the processing method using the transmission Bessel beam, the reflective Bessel beam can achieve higher precision processing and improve the yield of the processed workpiece 50.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reflective Bessel laser micro-nano processing device, characterized in that, The application relates to a laser beam shaping device and a laser beam shaping method. The laser beam shaping device comprises a light source assembly, a reflective Bessel assembly, a beam focusing assembly and a control assembly. The light source assembly comprises a laser and a transmission light path, the laser is adapted to emit a laser beam, the transmission light path is adapted to transmit the laser beam, the transmission light path comprises a first mirror, and the first mirror is adapted to transmit the laser beam to a first focal point. The reflective Bessel assembly is adapted to shape the laser beam into a Bessel beam and change the propagation direction of the Bessel beam to form a reflective Bessel beam. The reflective Bessel assembly comprises a second mirror group, a continuously variable adjustable beam expander and a reflective axicon mirror, the continuously variable adjustable beam expander is adapted to change the diameter of the laser beam at the first focal point, the expansion ratio of the continuously variable adjustable beam expander is adjustable to be 2:1-6:1, the reflective axicon mirror is adapted to convert the laser beam passing through the continuously variable adjustable beam expander into the Bessel beam, the incident spot of the reflective axicon mirror is 5mm, the diameter of the outgoing Bessel beam is 43um, and the second mirror group is adapted to change the propagation direction of the Bessel beam to form the reflective Bessel beam and converge the reflective Bessel beam to a second focal point. The beam focusing assembly is adapted to converge the reflective Bessel beam. 2.The reflective Bessel laser micro-nano processing device according to claim 1, wherein The control assembly is adapted to control the relative position between the focal point of the reflective Bessel beam and a workpiece. 3.The reflective Bessel laser micrometer and nanometer processing device according to claim 2, characterized in that, The beam focusing assembly comprises a microscope objective, the microscope objective is adapted to receive the reflective Bessel beam at the second focal point and focus the reflective Bessel beam to a third focal point.

4. A reflective Bessel laser micro-nano processing method based on the reflective Bessel laser micro-nano processing device according to any one of claims 1-3, characterized in that, The control assembly comprises a galvanometer, the galvanometer is adapted to change the position of the third focal point of the reflective Bessel beam. The laser beam shaping method comprises the following steps. The laser beam is emitted. The laser beam is expanded by the continuously variable adjustable beam expander. The laser beam expanded by the continuously variable adjustable beam expander is converted into the Bessel beam by the reflective axicon mirror. The propagation direction of the Bessel beam is changed by the second mirror group to form the reflective Bessel beam, and the reflective Bessel beam enters the beam focusing assembly. The reflective Bessel beam is focused to the workpiece.

5. The reflective Bessel laser micromachining method according to claim 4, wherein, The position relationship between the focal point of the reflective Bessel beam and the workpiece is adjusted. The laser beam is continuously variable expanded by the continuously variable adjustable beam expander, and the expansion ratio is 2:1-6:

1. 6.The reflective Bessel laser micromachining method according to claim 4, wherein, The Bessel beam passes through the second mirror group to change the propagation direction to form the reflective Bessel beam, and the reflective Bessel beam passes through the microscope objective for focusing. The position relationship between the focal point of the reflective Bessel beam and the workpiece is adjusted. 7.The reflective Bessel laser micromachining method according to claim 4, wherein, ​ The position relationship between the focusing point of the reflective Bessel beam and the workpiece is adjusted by a vibrating mirror.

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