Design method of laser ablation induced impulse based on composite pulse

Abstract

The invention discloses a composite pulse-based laser ablation induced impulse design method, which comprises the following steps: performing composite pulse laser ablation treatment on a target material by adopting first pulse laser and second pulse laser, and when the required laser ablation impulse is greater than a first impulse threshold, performing composite pulse laser ablation treatment in a front mode; when the required laser ablation impulse is between the second impulse threshold value and the first impulse threshold value, laser ablation treatment of composite pulses in a superposition mode is adopted; when the required laser ablation impulse is smaller than a second impulse threshold value, laser ablation treatment of a composite pulse in a rear mode is adopted; the first pulse width of the first pulse laser is smaller than the second pulse width of the second pulse laser; the second impulse threshold value is smaller than the first impulse threshold value. By applying the method, the ablation effect with higher impulse can be obtained, and different ablation impulses can be provided in different ablation treatment stages.

Description

Technical Field

[0001] The invention relates to the technical field of laser-matter interaction, and in particular to a design method for laser ablation induced impulse based on composite pulses. Background Art

[0002] During the interaction between laser and matter, such as the interaction between laser and target material, laser ablation impulse will be generated. As a propulsion parameter, impulse is defined as the cumulative effect of force over a period of time. Laser ablation impulse mainly comes from processes such as induced plasma, material peeling, and melt sputtering. It can serve various application scenarios that require laser ablation impact force loading control, such as laser processing, laser propulsion, and laser damage.

[0003] Composite pulse laser ablation refers to the use of lasers with different pulse types to irradiate materials in different time and space coupling modes to produce ablation. The impulse generated by this composite pulse laser ablation mode can be controlled by designing the time and space distribution relationship of different pulse lasers, thereby meeting different laser ablation impulse requirements during the interaction between laser and material (target material).

[0004] In recent years, researchers have conducted in-depth research on the basic principles of composite pulse laser-induced impulses and have extensively explored the internal physical mechanisms and effects of composite pulse laser ablation. There are two main types of time domain distribution of composite pulse laser action: the first type is that two lasers output simultaneously, and the second type is that two lasers output in stages. In the research of laser ablation based on composite pulses, the following issues are still unresolved:

[0005] (1) Under laser ablation conditions alone, the recoil impulse performance generated by laser-induced plasma needs to be improved;

[0006] (2) The ablation performance of the two laser composite pulses under the condition of changing composite timing needs to be improved;

[0007] (3) The ablation mechanism when the laser time domain distribution changes is not clearly understood. Summary of the invention

[0008] The purpose of the present invention is to provide a design method for composite pulse laser ablation induced impulse, so as to realize reasonable configuration of composite pulse laser ablation induced impulse to be adjustable and controllable.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] According to one aspect of the present invention, a method for designing a laser ablation induced impulse based on a composite pulse is provided, comprising the following steps:

[0011] The first pulse laser and the second pulse laser are used to perform a composite pulse laser ablation process on the target material.

[0012] When the required laser ablation impulse is greater than the first impulse threshold, a composite pulse laser ablation process in a pre-mode is adopted: after outputting a first pulse laser, a second pulse laser is output after a first time interval;

[0013] When the required laser ablation impulse is between the second impulse threshold and the first impulse threshold, a laser ablation process using a composite pulse in a 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, a post-mode composite pulse laser ablation process is adopted: after outputting the second pulse laser, the first pulse laser is output again after a second time interval;

[0015] The first pulse width of the first pulse laser is smaller than the second pulse width of the second pulse laser; and the second impulse threshold is smaller than the first impulse threshold.

[0016] According to one embodiment of the present invention, the first pulse laser is a femtosecond pulse laser, or a picosecond pulse laser, or a nanosecond pulse laser; the second pulse laser is a millisecond pulse laser, or a microsecond pulse laser.

[0017] According to one embodiment of the present invention, the second pulse laser is a millisecond pulse laser, and the laser energy of the millisecond pulse 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 pulse laser is a millisecond pulse laser. When the millisecond pulse laser is output, the millisecond pulse laser will heat the surface material of the target material to a molten state, and the surface material of the target material will not peel off.

[0019] According to one embodiment of the present invention, the first pulse laser is a nanosecond pulse laser. When the nanosecond pulse laser is output, the nanosecond pulse 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 pulse laser is a nanosecond pulse laser, and when the nanosecond pulse laser is output, the nanosecond pulse laser causes the surface material of the target material to be peeled off to form an ablation pit;

[0021] The second pulse laser is a millisecond pulse laser. When the millisecond pulse laser is output, the millisecond pulse laser is reflected multiple times by the morphology of the ablation pit, and a secondary induced impulse is formed on the surface of the ablation pit through multiple reflections and ablation.

[0022] According to an embodiment of the present invention, the value range of the first impulse threshold is 10-12 micronewton seconds; the value range of the second impulse threshold is 6-8 micronewton seconds.

[0023] According to an embodiment of the present invention, the value range of the first time interval is 0-2 milliseconds; the value range of the second time interval is 0-1 millisecond.

[0024] According to one embodiment of the present invention, the design method is implemented based on the following system, which includes:

[0025] A first laser 1, a second laser 2, a first focusing lens 3, a second focusing lens 4, a supporting 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 supporting base 5, the torsion pendulum 7 is fixed on the pivot 6 at its midpoint position, 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 first ablation point and the second ablation point are located at the same position. During the process of ablation of the target material 8 by the first pulse laser and / or the second pulse laser, laser ablation impulses are generated in the overlapping area of ​​the first and second ablation points.

[0027] The recoil force of the laser ablation impulse will push the torsion pendulum 7 to rotate around the pivot 6, and the first end 71 of the torsion pendulum 7 will undergo a first displacement, and the second end 72 of the torsion pendulum 7 will undergo a second displacement; the displacement sensor 9 monitors the second displacement generated by the second end 72 of the torsion pendulum 7, measures the second displacement distance, and calculates the size 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 relative to the pivot 6, so the first displacement distance is equal to the second displacement distance, and the size of the laser ablation impulse calculated according to the second displacement distance is the size of the laser ablation impulse generated at the ablation point on the target material.

[0029] The present invention provides a design method for laser ablation induced impulse based on composite pulses, which realizes different control modes to complete the composite pulse ablation process by controlling the output of different pulse lasers. Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The nanosecond pulse laser is placed 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. Compared with single pulse ablation, the size of the recoil impulse is further increased;

[0031] 2. In the superposition control mode of the composite pulse of nanosecond pulse laser superimposed on millisecond pulse laser, the laser output is adjusted, and the recoil impulse can be freely adjusted according to the needs, and the impulse is adjustable;

[0032] 3. The nanosecond pulse laser is placed in the post-control mode of the millisecond pulse laser, and the material is peeled off and evaporated, which increases the size of the recoil impulse.

[0033] 4. The three control modes of the composite pulse are used to adjust the impulse required by the ablated material or material. Different ablation impulses can also be provided in different ablation stages in terms of timing, which can effectively solve the problem of changes in laser energy absorption rate and obtain ablation effects with higher impulses. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 is a schematic diagram of a system for implementing composite pulse laser ablation according to an exemplary embodiment of the present invention.

[0036] Figure 2 is a flow chart of a method for designing composite pulse-based laser ablation induced impulse according to an exemplary embodiment of the present invention.

[0037] Figure 3 is a flow chart of implementing composite pulse laser ablation in a pre-control mode according to an exemplary embodiment of the present invention.

[0038] Figure 4 is a flow chart of implementing composite pulse laser ablation in superposition control mode according to an exemplary embodiment of the present invention.

[0039] Figure 5 is a flow chart of implementing composite pulse laser ablation in a post control mode according to an exemplary embodiment of the present invention.

[0040] Figure 6 3 is a comparison diagram of the laser ablation effects of compound pulse and single laser in three control modes according to an exemplary embodiment of the present invention.

[0041] Figure 73 is a comparison diagram of the laser ablation effect of a composite pulse and a single laser under different laser energies in different control modes according to an exemplary embodiment of the present invention.

[0042] Reference numerals:

[0043] 1-first laser; 2-second laser; 3-first focusing lens; 4-second focusing lens; 5-support base; 6-pivot; 7-torsion pendulum; 8-target material; 9-displacement sensor; 71-first end of torsion pendulum 7; 72-second end of torsion pendulum 7. DETAILED DESCRIPTION

[0044] In order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, words such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and effects. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and their order is not limited. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit them to be different.

[0045] It should be noted that, in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0046] In the present invention, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. The following at least one item (items) or similar expressions thereof refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, at least one item (items) of a, b or c can mean: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b, c can be single or multiple.

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0048] like Figure 1 As shown, a schematic diagram of the system for laser ablation-induced impulse based on composite pulses is given.

[0049] The system includes a first laser 1, a second laser 2, a first focusing lens 3, a second focusing lens 4, a supporting 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 supporting base 5 , the pendulum 7 is fixed on the pivot 6 at its midpoint position, the target material 8 is fixed on the first end 71 of the pendulum 7 ; and the displacement sensor 9 monitors the second end 72 of the pendulum 7 .

[0051] The first outgoing laser light 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 outgoing laser light 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 with each other.

[0052] During the process of ablating the target material 8 by the first emitted laser and / or the second emitted 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 push the torsion pendulum 7 to rotate around the pivot 6, and the first end 71 of the torsion pendulum 7 will undergo a first displacement, and the second end 72 of the torsion pendulum 7 will undergo a second displacement; the displacement sensor 9 monitors the second displacement generated by the second end 72 of the torsion pendulum 7, measures the second displacement distance, and calculates the size of the laser ablation impulse based on the second displacement distance. Since the first end 71 and the second end 72 are symmetrical points relative to the center of the pivot 6, the first displacement distance is equal to the second displacement distance, and the size of the laser ablation impulse calculated based on the second displacement distance is the size of the laser ablation impulse generated by the ablation point on the target material.

[0053] Composite pulse lasers are usually composed of two lasers with different pulse widths, including a main pulse laser and an auxiliary pulse laser. The main pulse laser is a long pulse laser, which is used for heat treatment of the target material, that is, heating, melting and evaporation. The auxiliary pulse laser is a short pulse laser, which is used to quickly process the target material, introduce defects to the surface of the material, and induce plasma to generate recoil impulse. During the laser ablation process, laser-induced plasma is generated. The recoil impulse generated by the laser-induced plasma helps to remove the melt in the ablation area and repair and reconstruct the processed surface. The application advantage of composite pulse lasers is also reflected in adjusting the pulse parameters of different lasers to achieve the purpose of optimizing the induced impulse performance. With the mature development of industrial lasers, composite pulse lasers have broad application potential in many fields such as laser processing, laser propulsion, and laser damage.

[0054] When different pulse lasers are output simultaneously, the characteristics of the pulse lasers, such as repetition frequency, pulse width, peak power, and the delay time when different pulse lasers are superimposed have a significant impact on the ablation process. When different pulse lasers are output in stages, the first pulse laser that ablates 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, which serves as the main pulse laser; the second emitted laser is a nanosecond laser, which serves as the auxiliary pulse laser. The first emitted laser and the second emitted laser are superimposed to form a composite pulse laser. In the ablation process of the composite pulse laser, the ablation process of the nanosecond laser can improve the absorption efficiency of the target material or improve the sputtering of the molten material, which can effectively improve the ablation performance of the millisecond laser. However, the ablation performance of the composite pulse laser of the nanosecond laser and the millisecond laser needs to be improved under the condition of the composite timing change.

[0056] like Figure 2 As shown, a flow chart of a design method of laser ablation induced impulse based on a composite pulse is given. The design method of laser ablation induced impulse based on a composite pulse includes the following steps:

[0057] Step S201: using a first pulse laser and a second pulse laser to perform a composite pulse laser ablation process on a target material.

[0058] Step S202: when the required laser ablation impulse is greater than the first impulse threshold, a composite pulse laser ablation process in a pre-mode is used: after outputting a first pulse laser, a 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 using a composite pulse in a superposition mode is performed: 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, a post-mode composite pulse laser ablation process is performed: 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 smaller than the second pulse width of the second pulse laser; and the second impulse threshold is smaller than the first impulse threshold.

[0062] The first impulse threshold has a value range of 10-12 micronewton seconds, the second impulse threshold has a value range of 6-8 micronewton seconds, the first time interval has a value range of 0-2 milliseconds, and the second time interval has a value range of 0-1 millisecond.

[0063] The first pulse laser is a femtosecond pulse laser, a picosecond pulse laser, or a nanosecond pulse laser; and the second pulse laser is a millisecond pulse laser, or a microsecond pulse laser.

[0064] like Figure 3 As shown, a schematic flow chart of the front mode of the composite pulse laser is given.

[0065] The auxiliary pulse laser is a nanosecond pulse laser, the main pulse laser is a millisecond pulse laser, and the nanosecond pulse laser is output before the millisecond pulse laser at a first time interval T1. The composite pulse laser is in the pre-mode to meet the laser ablation application with high impulse requirements. The control method of the composite pulse laser in the pre-mode includes the following steps:

[0066] Step S301, adjusting 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, outputting nanosecond pulse laser to ablate the surface of the irradiated area to form ablation pit morphology;

[0068] Step S303: after the first time interval T1, output millisecond pulse laser.

[0069] Step S304 , controlling the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation processes according to steps 302 and 303 .

[0070] The value range of the first time interval T1 is greater than 0 microseconds and less than 2000 microseconds. During the ablation process of the millisecond pulse laser, the morphology of the ablation pit reflects the millisecond pulse laser multiple times, which can effectively utilize the energy of the millisecond pulse laser and ensure that the energy is absorbed as much as possible. In addition, 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 heat energy to heat the ablation interface.

[0071] like Figure 4 As shown, a schematic diagram of the process of the superposition mode of the composite pulse laser is given.

[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 and output. The composite pulse laser is used to meet the laser ablation application with adjustable impulse requirements in the superposition mode. The control method of the composite pulse laser in the superposition mode includes the following steps:

[0073] Step S401, adjusting 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, outputting a millisecond pulse laser; at this time, since the energy threshold of the induced impulse is not reached, the target surface material will not be peeled off, and the millisecond pulse laser will heat the target surface material to a molten state;

[0075] Step S403, outputting nanosecond pulse laser within the pulse width range of the millisecond pulse laser; at this time, the surface material of the target material is peeled off to form an ablation pit;

[0076] Step S404 , controlling the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation processes according to steps 402 and 403 .

[0077] During the ablation process of millisecond pulse laser, the morphology of the ablation pit reflects the millisecond pulse laser multiple times, which can effectively utilize the energy of the millisecond pulse laser and ensure that the energy is absorbed as much as possible. In addition, multiple reflection ablation can modify the surface of the ablation pit to form secondary induced impulse, or the reflected laser is absorbed by the target material and converted into thermal energy to heat the ablation interface.

[0078] like Figure 5 As shown, a schematic diagram of the process flow of the post-mode of the composite pulse laser is given.

[0079] The auxiliary pulse laser is a nanosecond pulse laser, the main pulse laser is a millisecond pulse laser, and the nanosecond pulse laser is output after the millisecond pulse laser at a second time interval T2. The composite pulse laser is in a post-mode to meet laser ablation applications with low impulse requirements. The control method of the composite pulse laser in the post-mode includes the following steps:

[0080] Step S501, adjusting 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, outputting a millisecond pulse laser; at this time, since the energy threshold of the induced impulse is not reached, the target surface material will not be peeled off, and the millisecond pulse laser will heat the target surface material to a molten state;

[0082] Step S503, after the second time interval T2 of stopping outputting the millisecond pulse laser, outputting the nanosecond pulse laser; at this time, the surface material of the target material is peeled off to form an ablation pit;

[0083] Step S504 , controlling the nanosecond pulse laser and the millisecond pulse laser to perform multiple rounds of laser ablation processes according to steps 502 and 503 .

[0084] The value range of the second time interval T2 is greater than 0 microseconds and less than 1000 microseconds. During the ablation process of the millisecond pulse laser, the morphology of the ablation pit reflects the millisecond pulse laser multiple times, which can effectively utilize the energy of the millisecond pulse laser and ensure that the energy is absorbed as much as possible. In addition, the multiple reflection ablation can modify the surface of the ablation pit to form a secondary induced impulse, or the reflected laser is absorbed by the target material and converted into heat energy to heat the ablation interface.

[0085] The invention is applicable to the laser irradiation ablation process of various target materials such as metal working fluids, polymer working fluids and energetic working fluids. It can achieve the improvement of impulse in the ablation process and can optimize the ablation performance according to 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 1064nm, and the second laser is a millisecond laser with a wavelength of 808nm. The millisecond pulse laser and the nanosecond pulse laser are respectively converged on the same point on the surface of the target material through focusing lenses, and the irradiation angle of the two laser beams is 5°. The delay triggering of different pulses is controlled by the digital delay generator DG645. The target material, i.e., the target material, is fixed at the first end of the torsion pendulum beam, and the recoil impulse at the second end of the beam is measured by a displacement sensor. In the embodiment, the target material selected is a high-energy glycidyl azide polymer (GAP) as the target material, and the spot diameters of the nanosecond laser and the millisecond laser are adjusted to 900μm and 1200μm, respectively. The system shown in the experimental example can be set in a vacuum chamber, and the ambient pressure is set to 10Pa.

[0087] Embodiment 1:

[0088] The energy of the millisecond laser irradiating the target is set to 18 mJ, the pulse width is 1 ms, and the energy of the nanosecond laser is set to 130 mJ.

[0089] The trigger delay of the nanosecond pulse relative to the millisecond pulse is set to vary from -2ms to 2ms, and the experimental interval is 0.2ms. -2ms~0ms, 0ms~1ms, and 1ms~2ms correspond to the nanosecond pulse preceding, overlapping, and following the millisecond pulse, respectively.

[0090] like Figure 6 As shown, the impulse induced by the composite pulse ablation changes with the trigger delay, which highlights the change of the composite pulse ablation impulse under the three control modes. Figure 6In the figure, region A corresponds to the case where the impulse is greater than the first impulse threshold, and the 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 the 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 impulse threshold and the first impulse threshold, and the superposition control mode with adjustable impulse can be used to achieve laser ablation of the composite pulse. Figure 6 As shown in the figure, compared with single pulse ablation, the induced impulse of composite pulse laser ablation in the three control modes increased, which is consistent with the impulse induction mechanism under different laser control methods.

[0091] Embodiment 2:

[0092] The energy of the millisecond laser irradiating the target was set to 18 mJ and the pulse width was 1 ms. The energy of the nanosecond laser was set to 105 mJ, 130 mJ and 150 mJ respectively as a control group.

[0093] The trigger delay of the nanosecond pulse relative to the millisecond pulse was set to vary from 0 to 2 ms, and the experimental interval was 0.2 ms.

[0094] like Figure 7 As shown in the figure, the impulse induced by composite pulse ablation changes with the trigger delay at different output energies of nanosecond laser. It can be seen that with the increase of nanosecond pulse energy, the impulse generated by single pulse ablation is 4.81μN·s, 5.55μN·s and 6.72μN·s respectively.

[0095] The induced impulse of laser ablation of 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 the 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 the superposition control mode with adjustable impulse can be used to achieve laser ablation of composite pulses.

[0096] The energy of the nanosecond laser was set to 105mJ, 130mJ and 150mJ respectively. At different energies, there was an obvious boundary between area B and area C, and the boundary position was basically at the 1.0ms position.

[0097] In addition, a computer-readable storage medium storing a computer program may also be provided according to an exemplary embodiment of the present invention. The 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. The computer-readable recording medium is any data storage device that can store data read out 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 wave (such as data transmission through the Internet via a wired or wireless transmission path).

[0098] In addition, a computing device may be provided according to an exemplary embodiment of the present invention. The computing device includes a processor and a memory. The memory is used to store a computer program. The computer program is executed by the processor so that the processor executes the computer program of the design method of laser ablation induced impulse based on composite pulse according to an exemplary embodiment of the present invention.

[0099] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the drawings, etc. In the specification, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit can implement several functions listed in the specification. Certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0100] Although the present invention has been described in conjunction with specific features and embodiments thereof, it is apparent that various modifications and combinations may be made thereto without departing from the spirit and scope of the present invention. Accordingly, this specification and the accompanying drawings are merely exemplary illustrations of the present invention and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, the present invention is intended to include such modifications and variations if they fall within the scope of the present invention and its equivalents.

Claims

1. A design method for laser ablation induced impulse based on composite pulse, characterized in that: include: The first pulse laser and the second pulse laser are used to perform a composite pulse laser ablation process on the target material. When the required laser ablation impulse is greater than the first impulse threshold, a composite pulse laser ablation process in a pre-mode is adopted: after outputting a first pulse laser, a second pulse laser is output after a first time interval; When the required laser ablation impulse is between the second impulse threshold and the first impulse threshold, a laser ablation process using a composite pulse in a 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, a post-mode composite pulse laser ablation process is adopted: after outputting the second pulse laser, the first pulse laser is output again after a second time interval; The first pulse width of the first pulse laser is smaller than the second pulse width of the second pulse laser; and the second impulse threshold is smaller than the first impulse threshold.

2. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 1, characterized in that: 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.

3. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 2, characterized in that: The second pulse laser is a millisecond pulse laser, and the laser energy of the millisecond pulse laser is lower than the energy threshold of inducing impulse when triggered alone.

4. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 2, characterized in that: The second pulse laser is a millisecond pulse laser. When the millisecond pulse laser is output, the millisecond pulse laser will heat the surface material of the target material to a molten state, and the surface material of the target material will not be peeled off.

5. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 2, characterized in that: The first pulse laser is a nanosecond pulse laser. When the nanosecond pulse laser is output, the nanosecond pulse laser causes the surface material of the target material to be peeled off to form an ablation pit.

6. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 2, characterized in that: The first pulse laser is a nanosecond pulse laser. When the nanosecond pulse laser is output, the nanosecond pulse laser causes the surface material of the target material to be peeled off to form an ablation pit. The second pulse laser is a millisecond pulse laser. When the millisecond pulse laser is output, the millisecond pulse laser is reflected multiple times by the morphology of the ablation pit, and a secondary induced impulse is formed on the surface of the ablation pit through multiple reflections and ablation.

7. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 1, characterized in that: The value range of the first impulse threshold is 10-12 micronewton seconds; the value range of the second impulse threshold is 6-8 micronewton seconds.

8. The design method of pulsed laser induced impulse for laser ablation based on composite pulse according to claim 1, characterized in that: The value range of the first time interval is 0-2 milliseconds; the value range of the second time interval is 0-1 millisecond.

9. The design method of pulse laser induced impulse for laser ablation based on composite pulse 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 supporting 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 supporting base (5), the torsion pendulum (7) is fixed on the pivot (6) at its midpoint position, and the target material (8) is fixed to a first end (71) of the torsion pendulum (7); the displacement sensor (9) monitors a second end (72) of the torsion pendulum (7); A first pulse laser emitted by a first laser (1) passes through a first focusing lens (3) and is then aimed at a first ablation point on a target material (8); a second pulse laser emitted by a second laser (2) passes through a second focusing lens (4) and is then aimed at a second ablation point on a target material (8); the first ablation point and the second ablation point are located at the same position; during the process of ablation of the target material (8) by the first pulse laser and / or the second pulse laser, laser ablation impulses are generated in the overlapping area of ​​the first and second ablation points; The recoil force of the laser ablation impulse pushes the torsion pendulum (7) to rotate around the pivot (6), causing the first end (71) of the torsion pendulum (7) to undergo a first displacement, and the second end (72) of the torsion pendulum (7) to undergo a second displacement; the displacement sensor (9) monitors the second displacement generated by the second end (72) of the torsion pendulum (7), measures a second displacement distance, and calculates the size of the laser ablation impulse based on the second displacement distance.

10. The design method of pulse laser induced impulse for laser ablation based on composite pulse 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.

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