A design method for laser ablation induced impulse based on composite pulses
By designing a composite pulsed laser ablation process and utilizing the temporal and spatial distribution relationships of different pulsed lasers, the problem of poor impulse control in composite pulsed laser ablation was solved, achieving controllability and efficient impulse generation in the laser ablation process.
Patent Information
- Application Number
- CN202411913108.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2044-12-24
AI Technical Summary
In the existing technology, there is insufficient understanding of the recoil impulse performance of laser-induced plasma, the ablation efficiency under the change of the timing of the two lasers being combined, and the ablation mechanism, which leads to poor laser ablation control effect.
By employing the temporal and spatial distribution relationships of different pulsed lasers, a composite pulsed laser ablation process was designed, including a pre-processing mode, a superposition mode, and a post-processing mode. The laser ablation impulse was adjusted by controlling the output sequence and time interval of the first and second pulsed lasers.
It improves the laser energy absorption rate, enhances the adjustability and magnitude of the recoil impulse, and realizes controllability and efficient impulse generation in the laser ablation process.
Smart Images
Figure CN119989624B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of laser-matter interaction technology, and in particular to a design method for laser ablation-induced impulse based on composite pulses. Background Technology
[0002] In the interaction between laser and matter, such as the interaction between laser and target material, laser ablation impulse is generated. Impulse, as a propulsion parameter, is defined as the cumulative effect of force over a period of time. Laser ablation impulse mainly originates from processes such as induced plasma, material exfoliation, and molten material sputtering, and can serve various applications requiring laser ablation impact force loading control, including laser processing, laser propulsion, and laser damage.
[0003] Composite pulsed laser ablation refers to the ablation effect produced by irradiating materials with different pulse types of lasers using different temporal and spatial coupling methods. The impulse generated by this composite pulsed laser ablation mode can be controlled by designing the temporal and spatial distribution relationships of different laser pulses, thereby meeting the varying impulse requirements of laser ablation during the interaction between the laser and the material (target).
[0004] In recent years, researchers have conducted in-depth studies on the fundamental principles of impulse induced by composite pulsed lasers, extensively exploring the internal physical mechanisms and effects of composite pulsed laser ablation. The temporal distribution of composite pulsed laser action mainly falls into two categories: the first involves simultaneous output of both lasers, and the second involves phased output of the two lasers. In the research of laser ablation based on composite pulses, the following issues remain unresolved:
[0005] (1) Under laser ablation alone, the recoil impulse performance of laser-induced plasma needs to be improved;
[0006] (2) The ablation efficiency of the two laser composite pulses under the condition of varying composite timing needs to be improved;
[0007] (3) The ablation mechanism when the laser temporal distribution changes is not well understood. Summary of the Invention
[0008] The purpose of this invention is to provide a design method for laser ablation induced impulse based on composite pulses, so as to achieve adjustable and controllable configuration of composite pulse laser ablation induced impulse.
[0009] To achieve the above objectives, the present invention provides the following technical solution:
[0010] According to one aspect of the present invention, a method for designing laser ablation-induced impulse based on composite pulses is provided, comprising the following steps:
[0011] A composite pulse laser ablation process is performed on the target material using a first pulse laser and a second pulse laser.
[0012] When the required laser ablation impulse is greater than the first impulse threshold, the laser ablation process of composite pulse in the pre-emergence mode is adopted: after the first pulse laser is output, the second pulse laser is output after the first time interval.
[0013] When the required laser ablation impulse is between the second impulse threshold and the first impulse threshold, a composite pulse laser ablation process in superposition mode is adopted: after outputting the second pulse laser, the first pulse laser is output within the pulse width range of the second pulse laser.
[0014] When the required laser ablation impulse is less than the second impulse threshold, the laser ablation process of the composite pulse in the post-mode is adopted: after the second pulse laser is output, the first pulse laser is output again after a second time interval.
[0015] The first pulse width of the first pulse laser is less than the second pulse width of the second pulse laser; the second impulse threshold is less than the first impulse threshold.
[0016] According to one embodiment of the present invention, the first pulsed laser is a femtosecond pulsed laser, or a picosecond pulsed laser, or a nanosecond pulsed laser; the second pulsed laser is a millisecond pulsed laser, or a microsecond pulsed laser.
[0017] According to one embodiment of the present invention, the second pulsed laser is a millisecond pulsed laser, and the laser energy of the millisecond pulsed laser is lower than the energy threshold of the induced impulse when triggered alone.
[0018] According to one embodiment of the present invention, the second pulsed laser is a millisecond pulsed laser. When the millisecond pulsed laser is output, it heats the surface material of the target to a molten state, and the surface material of the target does not peel off.
[0019] According to one embodiment of the present invention, the first pulsed laser is a nanosecond pulsed laser. When the nanosecond pulsed laser is output, the nanosecond pulsed laser causes the surface material of the target material to be peeled off to form an ablation pit.
[0020] According to one embodiment of the present invention, the first pulsed laser is a nanosecond pulsed laser. When the nanosecond pulsed laser is output, the nanosecond pulsed laser causes the surface material of the target material to be peeled off to form an ablation pit.
[0021] The second pulsed laser is a millisecond pulsed laser. When the millisecond pulsed laser is output, it is reflected multiple times by the morphology of the ablation pit. After multiple reflections, it ablates the surface of the ablation pit and forms a secondary induced impulse.
[0022] According to one embodiment of the present invention, the first impulse threshold is in the range of 10-12 micronewtons; the second impulse threshold is in the range of 6-8 micronewtons.
[0023] According to one embodiment of the present invention, the first time interval is in the range of 0-2 milliseconds; the second time interval is in the range of 0-1 milliseconds.
[0024] According to one embodiment of the present invention, the design method is implemented based on a system comprising:
[0025] A first laser 1, a second laser 2, a first focusing lens 3, a second focusing lens 4, a support base 5, a pivot 6, a torsion pendulum 7, a target material 8, and a displacement sensor 9; the pivot 6 is fixed on the support base 5, the torsion pendulum 7 is fixed on the pivot 6 at its midpoint, and the target material 8 is fixed on the first end 71 of the torsion pendulum 7; the displacement sensor 9 monitors the second end 72 of the torsion pendulum 7.
[0026] The first pulse laser emitted by the first laser 1 passes through the first focusing lens 3 and is aimed at the first ablation point on the target material 8. The second pulse laser emitted by the second laser 2 passes through the second focusing lens 4 and is aimed at the second ablation point on the target material 8. The positions of the first ablation point and the second ablation point coincide. During the ablation of the target material 8 by the first pulse laser and / or the second pulse laser, a laser ablation impulse will be generated in the overlapping area of the first and second ablation points.
[0027] The recoil force of the laser ablation impulse will drive the pendulum 7 to rotate around the pivot 6, the first end 71 of the pendulum 7 will undergo a first displacement, and the second end 72 of the pendulum 7 will undergo a second displacement; the displacement sensor 9 monitors the second displacement generated by the second end 72 of the pendulum 7, measures the second displacement distance, and calculates the magnitude of the laser ablation impulse based on the second displacement distance.
[0028] According to one embodiment of the present invention, the first end 71 and the second end 72 of the torsion pendulum 7 are centrally symmetrical with respect to the pivot 6, so the first displacement distance is equal to the second displacement distance. The magnitude of the laser ablation impulse calculated based on the second displacement distance is the magnitude of the laser ablation impulse generated at the ablation point on the target material.
[0029] This invention provides a design method for laser ablation induced impulse based on composite pulses. By controlling the output of different pulsed lasers, different control modes are achieved to complete the composite pulse ablation process. Compared with the prior art, the beneficial effects of this invention are as follows:
[0030] 1. The nanosecond pulse laser is pre-positioned in the pre-control mode of the millisecond pulse laser output. The millisecond pulse laser can be reflected multiple times in the ablation pit, which improves the energy absorption rate of the target material and further enhances the magnitude of the recoil impulse compared with single-pulse ablation.
[0031] 2. In the superposition control mode of nanosecond pulse laser superimposed with millisecond pulse laser, the laser output and recoil impulse can be adjusted freely according to the requirements, and the impulse is adjustable;
[0032] 3. The nanosecond pulse laser is followed by the millisecond pulse laser in a post-control mode, causing the material to peel off and evaporate, thus increasing the magnitude of the recoil impulse.
[0033] 4. Three control modes of composite pulses are adopted, which can be adjusted according to the impulse required by the ablation material or material. Different ablation impulses can also be provided in different ablation stages according to the timing, which can effectively solve the problem of laser energy absorption rate variation and obtain ablation effect with higher impulse. Attached Figure Description
[0034] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:
[0035] Figure 1 This is a schematic diagram of a system for realizing laser ablation of composite pulses according to an exemplary embodiment of the present invention.
[0036] Figure 2 This is a flowchart of a design method for laser ablation-induced impulse based on composite pulses according to an exemplary embodiment of the present invention.
[0037] Figure 3 This is a flowchart illustrating the implementation of laser ablation of composite pulses using a pre-control mode according to an exemplary embodiment of the present invention.
[0038] Figure 4 This is a flowchart illustrating laser ablation of composite pulses using a superposition control mode according to an exemplary embodiment of the present invention.
[0039] Figure 5 This is a flowchart illustrating the laser ablation of composite pulses using a post-control mode according to an exemplary embodiment of the present invention.
[0040] Figure 6 This is a comparison diagram of the laser ablation effect of composite pulse and single laser ablation under three control modes according to an exemplary embodiment of the present invention.
[0041] Figure 7This is a comparison diagram of the laser ablation effect of composite pulses and single laser ablation under different laser energies in different control modes according to an exemplary embodiment of the present invention.
[0042] Figure label:
[0043] 1-First laser; 2-Second laser; 3-First focusing lens; 4-Second focusing lens; 5-Support base; 6-Pivot; 7-Pendulum; 8-Target material; 9-Displacement sensor; 71-First end of pendulum 7; 72-Second end of pendulum 7. Detailed Implementation
[0044] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.
[0045] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.
[0046] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c" can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.
[0047] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0048] like Figure 1 As shown, a schematic diagram of a system for laser ablation-induced impulse based on composite pulses is presented.
[0049] The system includes a first laser 1, a second laser 2, a first focusing lens 3, a second focusing lens 4, a support base 5, a pivot 6, a torsion pendulum 7, a target material 8, and a displacement sensor 9.
[0050] The pivot 6 is fixed on the support base 5, the torsion pendulum 7 is fixed on the pivot 6 at its midpoint, the target material 8 is fixed on the first end 71 of the torsion pendulum 7, and the displacement sensor 9 monitors the second end 72 of the torsion pendulum 7.
[0051] The first laser emitted by the first laser 1 passes through the first focusing lens 3 and is aimed at the first ablation point on the target material 8. The second laser emitted by the second laser 2 passes through the second focusing lens 4 and is aimed at the second ablation point on the target material 8. The positions of the first ablation point and the second ablation point coincide.
[0052] During the ablation of the target 8 by the first and / or second emitted lasers, a laser ablation impulse is generated in the overlapping area of the first and second ablation points. The recoil force of the laser ablation impulse drives the pendulum 7 to rotate around the pivot 6. The first end 71 of the pendulum 7 undergoes a first displacement, and the second end 72 of the pendulum 7 undergoes a second displacement. The displacement sensor 9 monitors the second displacement generated by the second end 72 of the pendulum 7, measures the second displacement distance, and calculates the magnitude of the laser ablation impulse based on the second displacement distance. Since the first end 71 and the second end 72 are centrally symmetrical points relative to the pivot 6, the first displacement distance is equal to the second displacement distance. The magnitude of the laser ablation impulse calculated based on the second displacement distance is the magnitude of the laser ablation impulse generated at the ablation point on the target.
[0053] Composite pulsed lasers typically consist of two superimposed lasers with different pulse widths: a master pulse and an auxiliary pulse. The master pulse is a long-pulse laser used for heat treatment of the target material, including heating, melting, and evaporation processes. The auxiliary pulse is a short-pulse laser used for rapid processing of the target material, introducing defects to the material surface and inducing plasma to generate a recoil impulse. During laser ablation, laser-induced plasma is generated. The recoil impulse generated by the laser-induced plasma helps remove molten material within the ablation zone and reshapes the processed surface. The advantages of composite pulsed lasers also lie in the ability to optimize the induced impulse performance by adjusting the pulse parameters of different lasers. With the mature development of industrial lasers, composite pulsed lasers have broad application potential in laser processing, laser propulsion, laser damage, and many other fields.
[0054] When different pulsed lasers are output simultaneously, the inherent characteristics of the pulsed lasers, such as repetition frequency, pulse width, and peak power, as well as the delay time when the different pulsed lasers are superimposed, have a significant impact on the ablation process. When different pulsed lasers are output in stages, the pulsed laser that first undergoes ablation usually introduces thermal stress or nonlinear absorption, which in turn affects the ablation process of subsequent lasers.
[0055] For example, the first emitted laser is a millisecond laser, serving as the main pulse laser; the second emitted laser is a nanosecond laser, serving as the auxiliary pulse laser. The first and second emitted lasers are superimposed to form a composite pulse laser. During the ablation process of the composite pulse laser, utilizing the ablation process of the nanosecond laser can improve the absorption efficiency of the target material or improve the sputtering of molten material, effectively improving the ablation performance of the millisecond laser. However, the ablation efficiency of the composite pulse laser using nanosecond and millisecond lasers under varying composite timing conditions needs further improvement.
[0056] like Figure 2 The diagram shows a flowchart of a method for designing laser ablation-induced impulse based on composite pulses. The method includes the following steps:
[0057] Step S201: Perform composite pulse laser ablation on the target material using a first pulse laser and a second pulse laser.
[0058] Step S202: When the required laser ablation impulse is greater than the first impulse threshold, laser ablation processing of composite pulse in pre-processing mode is adopted: after outputting the first pulse laser, the second pulse laser is output after a first time interval.
[0059] Step S203: When the required laser ablation impulse is between the second impulse threshold and the first impulse threshold, laser ablation processing of composite pulses in superposition mode is adopted: after outputting the second pulse laser, the first pulse laser is output within the pulse width range of the second pulse laser.
[0060] Step S204: When the required laser ablation impulse is less than the second impulse threshold, laser ablation processing with a composite pulse in post-processing mode is adopted: after outputting the second pulse laser, the first pulse laser is output again after a second time interval.
[0061] The first pulse width of the first pulse laser is less than the second pulse width of the second pulse laser; the second impulse threshold is less than the first impulse threshold.
[0062] The first impulse threshold ranges from 10 to 12 micronewtons; the second impulse threshold ranges from 6 to 8 micronewtons. The first time interval ranges from 0 to 2 milliseconds; the second time interval ranges from 0 to 1 millisecond.
[0063] The first pulse laser is a femtosecond pulse laser, a picosecond pulse laser, or a nanosecond pulse laser; the second pulse laser is a millisecond pulse laser or a microsecond pulse laser.
[0064] like Figure 3 The diagram shows a flowchart of the pre-mode of a composite pulsed laser.
[0065] The auxiliary pulse laser is a nanosecond pulse laser, and the main pulse laser is a millisecond pulse laser. The nanosecond pulse laser is output before the millisecond pulse laser by a first time interval T1. In the pre-emitter mode, the composite pulse laser is used to meet the needs of laser ablation applications requiring high impulse. The control method for the composite pulse laser in the pre-emitter mode includes the following steps:
[0066] Step S301: Adjust the laser energy of the millisecond pulse laser to be lower than the energy threshold of the induced impulse when triggered alone;
[0067] Step S302: Output nanosecond pulse laser to ablate the surface of the irradiated area to form an ablation pit morphology;
[0068] Step S303: After the first time interval T1, output a millisecond pulse laser.
[0069] Step S304: Control the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation process according to steps 302 and 303.
[0070] The first time interval T1 is greater than 0 microseconds and less than 2000 microseconds. During the millisecond pulse laser ablation process, the morphology of the ablation pit reflects the millisecond pulse laser multiple times, which can effectively utilize the energy of the millisecond pulse laser, ensure that the energy is absorbed as much as possible, and the multiple reflection ablation can modify the surface of the ablation pit to form a secondary induced impulse, or the reflected laser can be absorbed by the target material and converted into thermal energy to heat the ablation interface.
[0071] like Figure 4 The diagram shows a flow chart of the superposition mode of composite pulsed lasers.
[0072] The auxiliary pulse laser is a nanosecond pulse laser, and the main pulse laser is a millisecond pulse laser. The nanosecond pulse laser and the millisecond pulse laser are superimposed for output. In superposition mode, the composite pulse laser is used to meet laser ablation applications requiring adjustable impulse. The control method for the composite pulse laser in superposition mode includes the following steps:
[0073] Step S401: Adjust the laser energy of the millisecond pulse laser to be lower than the energy threshold of the induced impulse when triggered alone;
[0074] Step S402: Output millisecond pulse laser; At this time, since the energy threshold for induced impulse has not been reached, the surface material of the target will not be peeled off, and the millisecond pulse laser will heat the surface material of the target to a molten state.
[0075] Step S403: Output nanosecond pulse laser within the pulse width range of the millisecond pulse laser; at this time, the material on the target surface is peeled off, forming an ablation pit;
[0076] Step S404: Control the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation process according to steps 402 and 403.
[0077] During the millisecond pulsed laser ablation process, the morphology of the ablation pit reflects the millisecond pulsed laser multiple times, which can effectively utilize the energy of the millisecond pulsed laser and ensure that the energy is absorbed as much as possible. Furthermore, multiple reflections can modify the surface of the ablation pit to form a secondary induced impulse, or the reflected laser can be absorbed by the target material and converted into thermal energy to heat the ablation interface.
[0078] like Figure 5 As shown, a flowchart illustrating the post-mode of a composite pulsed laser is presented.
[0079] The auxiliary pulse laser is a nanosecond pulse laser, and the main pulse laser is a millisecond pulse laser. The nanosecond pulse laser is output after the millisecond pulse laser at a second time interval T2. In the post-emitter mode, the composite pulse laser is used to meet the needs of laser ablation applications requiring low impulse. The control method for the composite pulse laser in post-emitter mode includes the following steps:
[0080] Step S501: Adjust the laser energy of the millisecond pulse laser to be lower than the energy threshold of the induced impulse when triggered alone;
[0081] Step S502: Output millisecond pulse laser; At this time, since the energy threshold for induced impulse has not been reached, the surface material of the target will not be peeled off, and the millisecond pulse laser will heat the surface material of the target to a molten state.
[0082] Step S503: After the second time interval T2 of stopping the output of millisecond pulse laser, a nanosecond pulse laser is output; at this time, the material on the target surface is peeled off, forming an ablation pit;
[0083] Step S504: Control the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation process according to steps 502 and 503.
[0084] The second time interval T2 ranges from greater than 0 microseconds to less than 1000 microseconds. During the millisecond pulse laser ablation process, the morphology of the ablation pit reflects the millisecond pulse laser multiple times, which can effectively utilize the energy of the millisecond pulse laser, ensuring that the energy is absorbed as much as possible. Furthermore, multiple reflections can modify the surface of the ablation pit to form a secondary induced impulse, or the reflected laser can be absorbed by the target material and converted into thermal energy to heat the ablation interface.
[0085] This invention is applicable to laser irradiation ablation processes of various target materials, including metallic working materials, polymer working materials, and energetic working materials. It can improve the impulse during the ablation process and optimize the ablation performance based on the impulse induction mechanism under different modes.
[0086] according to Figure 1 As shown, in a specific embodiment of the present invention, the first laser is a nanosecond laser with a wavelength of 1064 nm, and the second laser is a millisecond laser with a wavelength of 808 nm. The millisecond and nanosecond pulsed lasers are focused onto the same point on the target surface by focusing lenses, with an irradiation angle of 5° between the two laser beams. The delay triggering of different pulses is controlled by a digital delay generator DG645. The target material, i.e., the target material, is fixed to the first end of a torsion beam, and the recoil impulse at the second end of the beam is measured using a displacement sensor. In this embodiment, high-energy glycidyl azide polymer (GAP) is selected as the target material. The spot diameters of the nanosecond and millisecond lasers are adjusted to 900 μm and 1200 μm, respectively. The system shown in the experimental example can be set up in a vacuum chamber with an environmental pressure of 10 Pa.
[0087] Example 1:
[0088] The energy of the millisecond laser irradiating the target was set to 18 mJ with a pulse width of 1 ms, and the energy of the nanosecond laser was set to 130 mJ.
[0089] The trigger delay of the nanosecond pulse relative to the millisecond pulse was set to vary from -2ms to 2ms, with an experimental interval of 0.2ms. -2ms to 0ms, 0ms to 1ms, and 1ms to 2ms correspond to the nanosecond pulse being placed before, overlapping with, and after the millisecond pulse, respectively.
[0090] like Figure 6 As shown, the change in impulse induced by composite pulse ablation with trigger delay highlights the changes in composite pulse ablation impulse under the three control modes. Figure 6In the diagram, region A corresponds to the case where the impulse is greater than the first impulse threshold, and a pre-control mode can be used to achieve laser ablation of the composite pulse; region C corresponds to the case where the impulse is less than the second impulse threshold, and a post-control mode can be used to achieve laser ablation of the composite pulse; region B corresponds to the case where the impulse is between the second and first impulse thresholds, and a superimposed control mode with adjustable impulse can be used to achieve laser ablation of the composite pulse. According to... Figure 6 As shown, compared with single-pulse ablation, the induced impulse of laser ablation with composite pulses under the three control modes is increased, which is consistent with the impulse induction mechanism under different laser control methods.
[0091] Example 2:
[0092] The target material was irradiated with a millisecond laser at an energy of 18 mJ and a pulse width of 1 ms. The nanosecond lasers were set to energies of 105 mJ, 130 mJ, and 150 mJ as control groups.
[0093] The trigger delay of the nanosecond pulse relative to the millisecond pulse was set to vary from 0 to 2 ms, with an experimental interval of 0.2 ms.
[0094] like Figure 7 As shown, the impulse induced by composite pulse ablation with trigger delay under different output energies of nanosecond lasers is presented. It can be seen that as the nanosecond pulse energy increases, the impulse generated by single-pulse ablation is 4.81 μN·s, 5.55 μN·s, and 6.72 μN·s, respectively.
[0095] The induced impulse of laser ablation by composite pulses also increases accordingly, and the influence of different trigger delay timings is basically the same under different output energies. For example, region C corresponds to the case where the impulse is less than the second impulse threshold, and a post-control mode can be used to achieve laser ablation of composite pulses; region B corresponds to the case where the impulse is between the second impulse threshold and the first impulse threshold, and a superposition control mode with adjustable impulse can be used to achieve laser ablation of composite pulses.
[0096] The nanosecond laser was set to energies of 105 mJ, 130 mJ and 150 mJ. At different energies, it showed a clear boundary between region B and region C, and the boundary position was basically at 1.0 ms.
[0097] Furthermore, an exemplary embodiment of the present invention may also provide a computer-readable storage medium storing a computer program. This computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to perform a design method for laser ablation-induced impulse based on a composite pulse, according to an exemplary embodiment of the present invention. This computer-readable recording medium is any data storage device capable of storing data readable by a computer system. Examples of computer-readable recording media include: read-only memory, random access memory, read-only optical disk, magnetic tape, floppy disk, optical data storage device, and carrier waves (such as data transmission via the Internet through wired or wireless transmission paths).
[0098] Furthermore, an exemplary embodiment of the present invention may also provide a computing device. The computing device includes a processor and a memory. The memory stores a computer program. The computer program is executed by the processor, causing the processor to perform a computer program for designing a laser ablation-induced impulse based on a composite pulse, according to an exemplary embodiment of the present invention.
[0099] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, disclosure, and other materials. In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple components. A single processor or other unit can implement several of the functions listed in the specification. While certain measures are described in different embodiments, this does not mean that these measures cannot be combined to produce good results.
[0100] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications fall within the scope of the invention and its equivalents, the invention is also intended to include such modifications and modifications.
Claims
1. A method for designing laser ablation-induced impulse based on composite pulses, characterized in that, include: A composite pulse laser ablation process is performed on the target material using a first pulse laser and a second pulse laser. When the required laser ablation impulse is greater than the first impulse threshold, the laser ablation process of composite pulse in the pre-emergence mode is adopted: after the first pulse laser is output, the second pulse laser is output after the first time interval. When the required laser ablation impulse is between the second impulse threshold and the first impulse threshold, a composite pulse laser ablation process in superposition mode is adopted: after outputting the second pulse laser, the first pulse laser is output within the pulse width range of the second pulse laser. When the required laser ablation impulse is less than the second impulse threshold, the laser ablation process of the composite pulse in the post-mode is adopted: after the second pulse laser is output, the first pulse laser is output again after a second time interval. The first pulse width of the first pulse laser is less than the second pulse width of the second pulse laser; the second impulse threshold is less than the first impulse threshold.
2. The design method for laser ablation-induced impulse based on composite pulses according to claim 1, characterized in that, The first pulsed laser is a femtosecond pulsed laser, or a picosecond pulsed laser, or a nanosecond pulsed laser; The second pulsed laser is a millisecond pulsed laser or a microsecond pulsed laser.
3. The method for designing laser ablation-induced impulse based on composite pulses according to claim 2, characterized in that, The second pulsed laser is a millisecond pulsed laser, and the laser energy of the millisecond pulsed laser is lower than the energy threshold of the induced impulse when triggered alone.
4. The design method for laser ablation-induced impulse based on composite pulses according to claim 2, characterized in that, The second pulsed laser is a millisecond pulsed laser. When the millisecond pulsed laser is output, it heats the surface material of the target to a molten state, and the surface material of the target does not peel off.
5. The method for designing laser ablation-induced impulse based on composite pulses according to claim 2, characterized in that, The first pulsed laser is a nanosecond pulsed laser. When the nanosecond pulsed laser is output, it causes the surface material of the target to be peeled off, forming an ablation pit.
6. The method for designing laser ablation-induced impulse based on composite pulses according to claim 2, characterized in that, The first pulsed laser is a nanosecond pulsed laser. When the nanosecond pulsed laser is output, the nanosecond pulsed laser causes the surface material of the target material to be peeled off, forming an ablation pit. The second pulsed laser is a millisecond pulsed laser. When the millisecond pulsed laser is output, it is reflected multiple times by the morphology of the ablation pit. After multiple reflections, it ablates the surface of the ablation pit and forms a secondary induced impulse.
7. The method for designing laser ablation-induced impulse based on composite pulses according to claim 1, characterized in that, The first impulse threshold ranges from 10 to 12 micronewtons; the second impulse threshold ranges from 6 to 8 micronewtons.
8. The method for designing laser ablation-induced impulse based on composite pulses according to claim 1, characterized in that, The first time interval ranges from 0 to 2 milliseconds; the second time interval ranges from 0 to 1 millisecond.
9. The method for designing laser ablation-induced impulse based on composite pulses according to claim 1, characterized in that, The design method is implemented based on the following system, which includes: A first laser (1), a second laser (2), a first focusing lens (3), a second focusing lens (4), a support base (5), a pivot (6), a torsion pendulum (7), a target material (8), and a displacement sensor (9); the pivot (6) is fixed on the support base (5), the torsion pendulum (7) is fixed on the pivot (6) at its midpoint, and the target material (8) is fixed on the first end (71) of the torsion pendulum (7); the displacement sensor (9) monitors the second end (72) of the torsion pendulum (7); The first pulse laser emitted by the first laser (1) is aimed at the first ablation point on the target material (8) after passing through the first focusing lens (3), and the second pulse laser emitted by the second laser (2) is aimed at the second ablation point on the target material (8) after passing through the second focusing lens (4). The positions of the first ablation point and the second ablation point coincide. During the ablation of the target material (8) by the first pulse laser and / or the second pulse laser, a laser ablation impulse will be generated in the overlapping area of the first and second ablation points. The recoil force of the laser ablation impulse will drive the pendulum (7) to rotate around the pivot (6), the first end (71) of the pendulum (7) will have a first displacement, and the second end (72) of the pendulum (7) will have a second displacement; the displacement sensor (9) monitors the second displacement generated by the second end (72) of the pendulum (7), measures the second displacement distance, and calculates the magnitude of the laser ablation impulse based on the second displacement distance.
10. The method for designing laser ablation-induced impulse based on composite pulses according to claim 9, characterized in that, The first end (71) and the second end (72) of the torsion pendulum (7) are centrally symmetrical with respect to the pivot (6), so the first displacement distance is equal to the second displacement distance. The magnitude of the laser ablation impulse calculated based on the second displacement distance is the magnitude of the laser ablation impulse generated at the ablation point on the target material.