Method and device for laser engraving on liquid film, and electronic equipment

Abstract

The present invention discloses a method, device, and electronic device for laser engraving on a liquid film. The technical solution includes: constructing a liquid film according to a preset formula, wherein the elasticity of the liquid film is close to zero, so that the thickness variation applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by the fluctuations in the liquid. According to the pattern information to be engraved on the surface of the liquid film, the laser emission parameters are set. The required information of different engraving patterns corresponds to different laser emission parameters. The liquid film is non-contact heated by the laser to construct a local gradient of heat-induced surface tension of the liquid film, stimulate heat-induced Marangoni flow on the surface of the liquid film, and construct thickness variation of the liquid film on the surface of the liquid film, thereby controlling the laser to engrave the corresponding engraving pattern on the liquid film according to the laser emission parameters. Based on the constructed liquid film with elasticity close to zero, the laser is controlled to complete engraving on the liquid film, filling the theoretical and technical gaps that currently exist in the inability to perform laser engraving on liquid films.

Description

Technical Field

[0001] The present disclosure relates to the technical field of liquid films, and in particular to a method and device for laser engraving on a liquid film, an electronic device, and a storage medium. Background Art

[0002] Laser engraving is a widely used process for processing solid materials. Using lasers as a processing medium, this engraving technique exploits the instantaneous melting and ablation of solid materials under laser irradiation, enabling non-contact, high-precision pattern engraving on solid surfaces. Currently, laser engraving is applicable to materials such as wood, acrylic, glass, two-tone panels, painted copper sheets, and density-coated panels. However, for fluid liquid materials, such as thin films, any disturbance applied to the film's surface is propagated by the various liquid waves, making the engraved pattern difficult to maintain as it is on solid materials. In other words, any physical structures created on the liquid surface, such as pits, are quickly propagated by the various liquid waves and, therefore, cannot be maintained, with the liquid surface quickly returning to its pre-disturbance state. Therefore, achieving stable, immovable patterns on liquid materials such as thin films is a pressing issue. Summary of the Invention

[0003] The present disclosure provides a method and device for laser engraving on a liquid film, an electronic device, and a storage medium, the main purpose of which is to achieve the engraving of a stable and immovable pattern composed of varying film thickness on the liquid film.

[0004] According to a first aspect of the present disclosure, there is provided a method for laser engraving on a liquid film, comprising:

[0005] constructing a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero so that thickness variations applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by fluctuations in the liquid;

[0006] According to the pattern information that needs to be engraved on the liquid film surface, the laser emission parameters are set. Different engraving pattern requirements correspond to different laser emission parameters.

[0007] The laser is controlled to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters.

[0008] Optionally, when the liquid film is a soap film, constructing the liquid film according to a preset formula includes:

[0009] Prepare a liquid film according to the preset formula, wherein the preset formula is such that the concentration of surfactant molecules is greater than the critical micelle concentration of the surfactant molecules;

[0010] The liquid film is drawn based on a preset liquid film manufacturing device to form a liquid film at a preset flow speed.

[0011] Optionally, the mass fraction of glycerol in the preset formula is 8%-12%, the mass fraction of carbonless ink is 2%, the concentration of surfactant molecules needs to be 4-6 times of their own critical micelle concentration, and the rest of the soap solution is deionized water.

[0012] Optionally, controlling the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters includes:

[0013] Transmitting a control signal to the laser based on the signal generator, so that the laser emits laser light according to the laser emission parameters;

[0014] The laser is controlled to focus on the liquid film through a preset lens group, and the position where the laser heats the liquid film can change over time;

[0015] Laser heating is used to create a local gradient in the surface tension of the liquid film, which stimulates thermally induced Marangoni flow on the liquid film surface and creates a change in the thickness of the liquid film.

[0016] An engraving pattern corresponding to the laser emission parameters is engraved on the liquid film.

[0017] Optionally, the method further includes:

[0018] After the laser light passes through the liquid film, it enters the beam stopper.

[0019] Optionally, controlling the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters includes:

[0020] The laser is incident on a hollow template containing an engraved pattern;

[0021] After the laser is incident on the hollow area of ​​the hollow template, the laser light of the engraved image corresponding to the hollow area is incident on the liquid film to complete the engraving of the liquid film.

[0022] Optionally, the method further includes:

[0023] During the engraving process, the interferometry method and / or the Schlieren method are used to observe and record the engraving process and results of the liquid film.

[0024] According to a second aspect of the present disclosure, there is provided an apparatus for laser engraving on a liquid film, comprising:

[0025] a construction unit, configured to construct a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero, so that thickness variations applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by fluctuations in the liquid;

[0026] A setting unit is used to set the laser emission parameters according to the pattern information to be engraved on the liquid film surface. Different engraving pattern requirement information corresponds to different laser emission parameters.

[0027] The engraving unit is used to control the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters.

[0028] Optionally, when the liquid film is a soap film, the construction unit includes:

[0029] a configuration module, configured to prepare a liquid film according to the preset formula, wherein the preset formula is such that the concentration of surfactant molecules is greater than the critical micelle concentration of the surfactant molecules;

[0030] The construction module is used to draw the liquid film based on a preset liquid film manufacturing device to form a liquid film at a preset flow speed.

[0031] Optionally, the mass fraction of glycerol in the preset formula is 8%-12%, the mass fraction of carbonless ink is 2%, the concentration of surfactant molecules needs to be 4-6 times of their own critical micelle concentration, and the rest of the soap solution is deionized water.

[0032] Optionally, the engraving unit is further used for:

[0033] Transmitting a control signal to the laser based on the signal generator, so that the laser emits laser light according to the laser emission parameters;

[0034] The laser is controlled to focus on the liquid film through a preset lens group, and the position where the laser heats the liquid film can change over time;

[0035] Laser heating is used to create a local gradient in the surface tension of the liquid film, which stimulates thermally induced Marangoni flow on the liquid film surface and creates a change in the thickness of the liquid film.

[0036] An engraving pattern corresponding to the laser emission parameters is engraved on the liquid film.

[0037] Optionally, the device further includes:

[0038] A processing unit for injecting the laser light into the beam terminator after the laser light passes through the liquid film.

[0039] Optionally, the engraving unit is further used for:

[0040] The laser is incident on a hollow template containing an engraved pattern;

[0041] After the laser is incident on the hollow area of ​​the hollow template, the laser light of the engraved image corresponding to the hollow area is incident on the liquid film to complete the engraving of the liquid film.

[0042] Optionally, the device further includes:

[0043] The recording unit is used to observe and record the engraving process and results of the liquid film by using an interference method and / or a schlieren method during the engraving process.

[0044] The present disclosure provides a method and apparatus, electronic device, and storage medium for laser engraving on a liquid film. The liquid film is constructed according to a preset recipe, wherein the elasticity of the liquid film is close to zero, so that thickness variations applied to the liquid film are retained on the surface of the liquid film and are not propagated by fluctuations in the liquid. Laser emission parameters are then set based on the desired pattern to be engraved on the liquid film surface. Different laser emission parameters correspond to different desired engraving patterns, and the laser is controlled based on these laser emission parameters to engrave the corresponding pattern on the liquid film.

[0045] Based on a liquid film constructed with near-zero elasticity, a laser is controlled to engrave the liquid film, filling the current theoretical and technological gaps in laser engraving on liquid films. The liquid film is constructed according to a preset recipe, where its elasticity is near zero, so that thickness variations applied to the liquid film are retained on the surface and are not propagated by fluctuations in the liquid. Laser emission parameters are then set based on the desired pattern to be engraved on the liquid film surface. Different laser emission parameters correspond to different engraving requirements, and the laser is controlled to engrave the corresponding pattern on the liquid film based on these laser emission parameters. Based on the desired pattern, a laser is controlled to engrave the corresponding pattern on the liquid film.

[0046] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are provided to facilitate a better understanding of the present invention and do not constitute a limitation of the present disclosure.

[0048] Figure 1 A schematic flow chart of a method for laser engraving a liquid film provided in an embodiment of the present disclosure;

[0049] Figure 2 A schematic diagram of different laser engraving effects produced on a liquid film under different operating conditions provided by an embodiment of the present disclosure;

[0050] Figure 3A schematic diagram of a device for laser engraving on a liquid film and its optical path provided in an embodiment of the present disclosure;

[0051] Figure 4 A side view of a device for laser engraving on a liquid film and its optical path provided in an embodiment of the present disclosure;

[0052] Figure 5(a) to Figure 5(c) Schematic diagram of different laser engraving effects produced on a liquid film under different variations of operation provided by an embodiment of the present disclosure;

[0053] Figure 6 A schematic diagram of a device for generating a "T"-shaped laser pulse as shown in FIG5(c) through a "T"-shaped hollow template and its optical path provided in an embodiment of the present disclosure;

[0054] Figure 7 An optical path diagram for visualizing the flow of a laser-engraved liquid film provided in an embodiment of the present disclosure;

[0055] Figure 8 Another optical path diagram for visualizing the flow of a laser-engraved liquid film provided in an embodiment of the present disclosure;

[0056] Figure 9 A schematic diagram of an output control signal to a laser for engraving a liquid film provided by an embodiment of the present disclosure;

[0057] Figure 10 A schematic structural diagram of a liquid film laser engraving device provided in an embodiment of the present disclosure;

[0058] Figure 11 A schematic structural diagram of another liquid film laser engraving device provided in an embodiment of the present disclosure;

[0059] Figure 12 A schematic block diagram of an exemplary electronic device 300 provided in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION

[0060] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0061] The following describes a method, device, electronic device, and storage medium for laser engraving of a liquid film according to embodiments of the present disclosure with reference to the accompanying drawings.

[0062] Figure 1A schematic flow chart of a method for laser engraving a liquid film provided in an embodiment of the present disclosure.

[0063] like Figure 1 As shown, the method comprises the following steps:

[0064] Step 101: constructing a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero, so that the thickness variation applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by the fluctuation in the liquid;

[0065] The embodiments of this application utilize the property that the elasticity of a liquid film approaches zero when its surfactant concentration is high (the concentration of surfactant molecules is greater than its critical micelle concentration). At this point, the propagation velocity of the elastic symmetric wave in the liquid film is close to zero. In other words, the symmetrical thickness variation imposed on the liquid film is not propagated by the wave, but is retained on the liquid film surface and flows with the liquid film. The carbon-free ink in the liquid film formula is intended to increase the soap film's absorption of laser energy, thereby achieving the effect of laser engraving on the liquid film.

[0066] Special note: This application uses the phrase "close to zero" throughout this application to describe the elasticity of the liquid film constructed according to the preset recipe and the propagation velocity of the symmetric elastic wave in the liquid film. Strictly speaking, with respect to liquid film elasticity, the phrase "close to zero" throughout this application indicates that the elasticity of the liquid film constructed according to the preset recipe is within a range of approximately 0 mN / m (millinewton / meter) to 0.02 mN / m (millinewton / meter). With respect to the propagation velocity of the symmetric elastic wave in the liquid film, taking a liquid film with a thickness of 20 microns as an example, the phrase "close to zero" throughout this application indicates that the propagation velocity of the symmetric elastic wave in the liquid film constructed according to the preset recipe is within a range of approximately 0 m / s (meter / second) to 0.05 m / s (meter / second). Therefore, in fact, for the liquid film described in this application that flows rapidly at a speed of about 1m / s (meter / second) to 3m / s (meter / second), the elasticity of the liquid film and the propagation speed of the elastic symmetric wave in the liquid film are both very small values, and can be considered to be zero in this application.

[0067] At this time, a heat-induced local gradient of the liquid film's surface tension is constructed by laser heating, stimulating heat-induced Marangoni flow on the liquid film surface, thereby constructing a variation in the thickness of the liquid film on the liquid film surface, i.e., various engraved patterns (e.g., pits, grooves, etc.). Specifically, the Marangoni flow constructed on the liquid film by laser heating in the present disclosure means that the surface tension of the liquid film at the laser-heated position decreases compared to the surface tension of the liquid film at the non-laser-heated position. This localized surface tension gradient of the liquid film causes the fluid at the low surface tension position to flow toward the high surface tension position, i.e., the liquid film fluid at the laser-heated position flows toward the surrounding non-laser-heated liquid film area, thereby causing the liquid film to form a pit structure with a thinner thickness at the laser-heated position, i.e., the engraved pattern constructed on the liquid film surface by laser heating.

[0068] Moreover, for the liquid film prepared using the solution formula given in the present disclosure, since the elasticity of the liquid film is close to zero, the above-mentioned engraved pattern on the liquid film will not be propagated by the fluctuations in the liquid such as elastic symmetric waves, but will remain on the surface of the liquid film. For the flowing liquid film, these pits that are stably maintained on the surface of the liquid film will also flow with the soap film. In the embodiment of the present application, liquid materials such as liquid films exhibit the same physical properties as solid materials. The embodiment of the present application achieves the process effect of laser engraving on liquid materials such as liquid films through the above-mentioned process principles.

[0069] It is particularly important to emphasize that during the laser heating process of the present disclosure, the engraved pattern, which is stable relative to the flowing liquid film, is created on the surface of the flowing liquid film. Phase transitions such as evaporation or boiling of the liquid in the liquid film are not involved. The pit-like engraved structures created on the liquid film by laser heating are not derived from phase transitions such as vaporization of the liquid in the liquid film. The thinning engraved structures, such as pits, created on the liquid film by laser heating are all caused by the aforementioned heat-induced surface tension gradient of the liquid, i.e., the heat-induced Marangoni flow on the liquid film surface, which is essentially derived from the temperature dependence of the liquid surface tension. In practice, laser heating can induce a sufficiently strong Marangoni flow at the heated location of the liquid film by only about 3 to 5 degrees Celsius, thereby achieving a very noticeable laser engraving effect on the liquid film. This temperature increase of about 3 to 5 degrees Celsius at the laser-heated location is far from enough to induce phase transitions such as boiling for a liquid initially at room temperature (25 degrees Celsius). Similarly, for the liquid film flowing at a speed of about 1 m / s to 3 m / s, the evaporation phase change caused by the above-mentioned heating and temperature increase can be ignored. Therefore, the principle proposed in this disclosure does not involve the phase change of the liquid film under the action of the laser. As mentioned above, the engraving principle of this disclosure is essentially derived from the heat-induced surface tension gradient on the liquid film caused by laser heating, that is, the heat-induced Marangoni flow on the surface of the liquid film. The maintenance of the engraved structure on the surface of the liquid film under the formula given in this disclosure comes from the near-zero elasticity of the liquid film under the formula. This is particularly emphasized here.

[0070] Step 102: setting the laser emission parameters according to the pattern information to be engraved on the liquid film surface.

[0071] The heating position of the laser on the liquid film may vary with time, and different engraving pattern requirement information corresponds to different laser emission parameters (including the change of the heating position of the laser on the liquid film with time).

[0072] Setting the laser's continuous or pulsed output mode, as well as output parameters like frequency, power, and duty cycle, primarily controls some fundamental properties of laser engraving, such as the size and depth of the engraved pits or grooves. However, the spatial location of the laser's focused heating remains unchanged, meaning the laser's propagation path remains unchanged.

[0073] Furthermore, narrowing the soap film flow channel increases the film thickness at the same flow rate, enhancing the heat transfer effect. Consequently, the engraved pits become larger and deeper under the same laser parameters. Conversely, widening the soap film flow channel decreases the film thickness at the same flow rate, weakening the heat transfer effect. Consequently, the engraved pits become smaller and shallower under the same laser parameters. This demonstrates a method for controlling the size and depth of laser engraved patterns on liquid films.

[0074] Although a stationary laser beam can carve a series of continuous pits or grooves on the liquid film due to the relative flow of the liquid film, in order to carve a richer pattern on the liquid film, the position where the laser is focused and heated on the liquid film needs to be controlled. This application provides two methods for controlling the focus and heating position of the laser on the liquid film: a mechanical multi-axis control method and a high-speed laser spatial scanning method.

[0075] The process effect of laser engraving on liquid film can be greatly enriched and improved by adjusting the laser output parameters and heating position. Generally speaking, on the liquid film, the focused laser is equivalent to a "knife". Adjusting the output parameters of the laser itself changes the thickness, discontinuity, depth and other line characteristics of the lines engraved by this "knife". Controlling the heating position of the laser on the liquid film is equivalent to using this "knife" to engrave various different patterns at different positions of the liquid film.

[0076] Step 103 : Controlling the laser to carve a corresponding engraving pattern on the liquid film according to the laser emission parameters.

[0077] In actual operation, when the laser outputs continuously, the laser can carve a continuous groove behind the position where the flowing liquid film is focused and irradiated; when the laser outputs pulses, the laser can carve a series of pits behind the position where the flowing liquid film is focused and irradiated, and the depth, size and distribution of the pits on the liquid film can be controlled by adjusting the output parameters of the laser; when the output frequency of the pulsed laser is high, the pits arranged in a series will be connected into a continuous groove.

[0078] When a high-speed scanning mirror system or a galvanometer system is used to quickly change the spatial position of the laser so that it is focused by the lens group and then quickly scanned on the flowing liquid film, a variety of rich patterns can be engraved on the flowing soap film in conjunction with a CNC system, such as a curved and continuous sinusoidal groove or a smiley face pattern.

[0079] In actual operation, the laser used is not limited to one beam, and multiple laser beams can be used to simultaneously perform laser engraving on the liquid film according to the requirements of the engraving pattern.

[0080] In general, the focused laser acts like a "knife" on the liquid film. Adjusting the laser's output parameters changes the thickness, continuity, depth, and other characteristics of the lines carved by the "knife." The high-speed scanning mirror or galvanometer system controls the trajectory of the lines carved by the "knife," thereby determining the pattern carved on the liquid film. Of course, this also requires consideration of parameters such as the liquid film's flow rate.

[0081] Regardless of whether a mechanical multi-axis motion control method is used or a high-speed scanning mirror or galvanometer system is used, it is necessary to combine the engraving pattern to be engraved on the liquid film and parameters such as the flow rate of the liquid film itself. The position of the laser focus irradiation point on the liquid film changes with time in advance on the CNC system, and then the speed and position of the laser scanning are controlled by the CNC system to engrave the desired pattern on the liquid film.

[0082] like Figure 2 As shown, Figure 2 (a) shows a flowing liquid film 6 without any laser engraving. When a stable laser beam is focused and irradiated on the flowing soap film, and its output frequency and duty cycle distribution are set accordingly, a series of pits or grooves with the corresponding distribution pattern will be engraved behind the focused irradiation point. Figure 2 (b) shows a liquid film 6 engraved by a pulsed laser output at a fixed frequency and duty cycle, and a series of uniformly arranged regular pits 8 engraved thereon. 7 is the focused irradiation point of a stable pulsed laser beam on the flowing soap film 6. Figure 2 (c) is a liquid film 6 engraved by a continuously output laser and a continuous groove 18 engraved thereon. 17 is a focused irradiation point of a stable continuously output laser beam on the flowing soap film 6; Figure 2 (d) shows a liquid film 6 with a customized pit pattern and a series of pits 20 engraved therein that meet the customized pattern. 19 shows the focused illumination point of a stable laser beam with a customized frequency and duty cycle distribution on the flowing soap film 6. Therefore, the process effect of laser engraving on liquid films in this embodiment of the application can be greatly enhanced by adjusting the laser output parameters.

[0083] The present disclosure provides a method for laser engraving a liquid film. The method constructs a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero. Laser emission parameters are set based on the thickness of the liquid film and the desired engraving pattern. Different engraving requirements correspond to different laser emission parameters. The laser is then controlled to engrave the corresponding engraving pattern on the liquid film based on the laser emission parameters. The present embodiment, based on a constructed liquid film with close to zero elasticity, controls the laser to engrave the liquid film, thereby filling the current theoretical and technical gaps in laser engraving on liquid films.

[0084] The subsequent embodiments use a soap film constructed from soap liquid as an example to illustrate how to achieve laser engraving on a liquid film. However, it should be clear that this description is not intended to limit the liquid film to only a soap film, but can also include any liquid film that can meet the working principle of this application, that is, a liquid film with elasticity close to zero.

[0085] Below, using soap films as an example, we will introduce common methods for constructing liquid films. Currently, there are many widely used processes for constructing soap films. The simplest method involves blowing soap bubbles, which are a type of soap film with a large curvature. Alternatively, if a flat soap film is desired, a commonly used method involves drawing it using two thin wires (mostly made of nylon). Specifically, the two wires are suspended vertically, their upper ends connected to the nozzles of an upper reservoir for storing liquid soap. Their lower ends are attached to a set of weights, which keep the wires taut. When the nozzle of the upper reservoir is opened, the soap liquid in the upper reservoir flows down the two wires, driven by gravity, and flows into the lower reservoir, which is placed under the lower weights. The soap liquid that flows into the lower reservoir is then pumped back to the upper reservoir via a peristaltic pump, thus forming a continuous soap liquid flow cycle. At this point, using multiple sets of thin hooks to gently pull the two thin threads apart, a stable, flowing soap film driven by gravity is formed. The flow rate of this flowing soap film can be controlled by the peristaltic pump described above. Hereinafter, the flowing soap film constructed using this method will be referred to as a "gravity-driven soap film." It should be emphasized that these examples only list a few common soap film construction methods. In reality, many other methods can be used to create soap films.

[0086] It should be noted that the embodiments of this application focus on the process of laser engraving on liquid films such as soap films. They do not address the preliminary preparation steps involved in constructing soap films, nor are they limited to the use of any existing soap film construction methods. To demonstrate the process principles and effects of laser engraving on liquid films, the embodiments of this application will use the aforementioned "gravity-driven soap film" as an example for introduction and explanation.

[0087] Taking a soap film as an example, constructing the liquid film according to a predetermined formula includes: the predetermined formula includes a concentration of surfactant molecules greater than the surfactant's critical micelle concentration; and drawing the liquid film using a predetermined liquid film manufacturing device to form a liquid film at a predetermined flow rate. Exemplarily, the predetermined formula includes a glycerin fraction of 8%-12% by mass, a carbonless ink fraction of 2% by mass, a surfactant concentration of 4-6 times its critical micelle concentration, and the remainder of the soap solution consisting of deionized water.

[0088] Since the embodiment of the present application utilizes the characteristic that the elasticity of the soap film is close to zero in the high concentration region (the concentration of surfactant molecules is greater than its own critical micelle concentration), there are many types of surfactant molecules to choose from in the soap film solution used in the embodiment of the present application, such as the classic sodium dodecyl sulfate (molecular formula: C 12 H 25 SO4Na, English name: Sodium dodecyl sulfate, abbreviated as: SDS), and hexadecyltrimethylammonium bromide (molecular formula: C 19 H 42 BrN, English name: Cetyltrimethylammonium Bromide, abbreviated as: CTAB).

[0089] Taking sodium dodecyl sulfate (SDS) as an example, the critical micelle concentration of sodium dodecyl sulfate molecules is about 5 mol / m 3 (mol / m3). Then, when sodium lauryl sulfate is selected as the surfactant molecule in the soap solution, the molecular concentration of sodium lauryl sulfate in the soap solution must be 20 mol / m 3 to 30 mol / m 3 about.

[0090] In addition to adding the above-mentioned surfactant molecules in pure form directly to the soap solution, another relatively simple method is to add dishwashing liquid containing the above-mentioned surfactant molecules to the soap solution. By adding dishwashing liquid in this way, the surfactant molecules can be added to the soap solution.

[0091] Taking a dishwashing liquid containing sodium lauryl sulfate molecules as an example, the mass fraction of 1% of this dishwashing liquid in the soap solution corresponds to approximately 10 mol / m of sodium lauryl sulfate molecules in the soap solution. 3 In other words, a mass fraction of approximately 0.5% of this dishwashing liquid in the soap solution is equivalent to the critical micelle concentration of sodium lauryl sulfate molecules. Therefore, if this dishwashing liquid is added, the mass fraction of the dishwashing liquid in the preset soap solution formula needs to be around 2%-3%.

[0092] The addition of carbon-free ink is to increase the absorption of laser energy by the soap film, especially for lasers in the visible light band, such as green lasers with a wavelength of 532nm, so as to achieve better laser engraving effects on the soap film. The 2% mass fraction of carbon-free ink was obtained through repeated experiments. According to Beer-Lambert's law: τ(λ)=(I t / I0) λ =exp(-k(λ)L), where I0 and I t are the incident and outgoing light intensities, respectively, and τ(λ) is the transmittance. For a liquid film with an optical path length L for the laser to pass perpendicularly through the liquid film (i.e., the film thickness), the addition of carbon-free ink essentially increases the soap film solution's absorption coefficient k(λ) for light of wavelength λ, thereby reducing the transmittance τ(λ) of light of wavelength λ after passing through the soap film, thereby increasing the soap film's absorption rate of laser energy. Conversely, if carbon-free ink is not added to the soap solution, the soap film solution's absorption coefficient k(λ) for light of this wavelength will be insufficient. Furthermore, because the soap film is only micrometer-thick, meaning the optical path length L required for absorbing laser energy is too short, the soap film will absorb very little laser energy, resulting in minimal heating of the soap film by the laser, making it difficult to achieve a good laser engraving effect.

[0093] In addition, lasers in the infrared band can also be used. According to the absorption spectrum of soap liquid to light waves of various bands, soap liquid has a larger absorption coefficient k(λ) for lasers in the infrared band, which can further improve the absorption rate of the soap film to the laser energy. However, since infrared lasers are invisible to the human eye, the process of using infrared lasers to perform laser engraving on liquid films is more dangerous. A corresponding optimization method is to co-beam the infrared laser with a beam of visible light laser for indication, so that the human eye can judge the position of the infrared laser through the visible indication laser, thereby reducing the risk of using infrared lasers to perform laser engraving on liquid films. In the following, the embodiments of the present application are still introduced and explained using a visible light laser with a wavelength of 532nm as an example.

[0094] Furthermore, the present embodiment utilizes carbonless ink (non-carbon ink), meaning that the ink contains no carbon particles, to prevent the carbon particles from affecting the flow of the micron-thick soap film. Preferably, the carbonless ink is a black ink with a high blackness, such as non-carbon black ink.

[0095] After preparing the soap liquid according to the above special formula, it is recommended to place the soap liquid in a beaker and stir it with a magnetic stirrer at a speed of about 1000 rpm (revolutions per minute) for 20 to 30 minutes to fully dissolve the components in the soap liquid. After stirring, it needs to be left to stand for 5 to 10 minutes, and then the foam layer floating above the soap liquid is removed. At this point, a special soap liquid that can be used to construct a soap film for laser engraving is obtained. The configured soap liquid is black and emits an aromatic smell. Its overall fluid state is very close to that of ordinary pure water. However, the difference is that due to the presence of surfactant molecules, the surface tension of the soap liquid is much lower than that of pure water, so the soap liquid can be used to construct a stable flowing soap film with a thickness of microns.

[0096] Here, it should be emphasized that the viscosity of the soap solution used in the embodiment of the present application is extremely low. Quantitatively speaking, the viscosity of the soap solution used in the embodiment of the present application is only 1.17 mPa·s at 25 degrees Celsius, and the viscosity of pure water at 25 degrees Celsius is 0.90 mPa·s. It can be seen that the viscosity of the soap solution used in the embodiment of the present application is very close to the viscosity of pure water. In addition, the dimensionless number (Ohnesorge number) used to describe the relative importance of viscosity in the soap film flow is only on the order of Among them, Oh is the dimensionless Ohnesorge number, μ is the dynamic viscosity of the soap film solution, ρ is the density of the soap film solution, h is the thickness of the soap film, and σ is the surface tension of the soap film. Therefore, the viscosity of the soap film solution used in the embodiment of the present application can be ignored, which is fundamentally different from fluids such as viscous fluids or melts with extremely high viscosity. In addition, the soap film solution used in the embodiment of the present application is an ordinary Newtonian fluid like pure water, rather than a non-Newtonian fluid with complex physical properties. In summary, the physical properties of the soap film solution used in the embodiment of the present application are similar to those of pure water, and are fundamentally different from high-viscosity fluids or non-Newtonian fluids with complex components and complex states; the technology disclosed in the embodiment of the present application is completely different from the related technology of using lasers to heat complex fluids such as high-viscosity fluids, molten fluids, non-Newtonian fluids, complex component fluids, etc. to achieve their ablation, softening, vaporization, melting and other effects, and is specially emphasized and explained here.

[0097] The embodiments of this application are directed to a soap solution with a specific formulation that closely resembles pure water in overall physical properties, and the related principles and techniques for laser engraving on a soap film with this specific formulation. In this embodiment of the application, due to the soap film's absorption of laser energy, the temperature of the soap film at the location irradiated by the laser increases locally compared to the temperature of the soap film at locations not irradiated by the laser. The core physical property altered by laser heating of the soap film in this embodiment of the application is the local surface tension of the soap film. This laser engraving process is achieved through the thermally induced Marangoni effect on the soap film surface, i.e., the thermally induced Marangoni flow on the soap film surface.

[0098] After preparing the soap liquid with the above-mentioned special formula, a stable flowing soap film with a thickness of micrometers can be produced using the soap liquid with the special formula by using the construction method of the "gravity-driven soap film" in the above-mentioned embodiment. Generally speaking, the flow rate of the soap film can be set within the range of 10 milliliters per minute (ml / min) to 40 milliliters per minute (ml / min) by a peristaltic pump. The width of the soap film flow channel, that is, the distance between the two thin lines in the gravity-driven soap film, can be adjusted according to actual conditions. The thickness of the flowing soap film can generally be within the range of 5 microns to 40 microns, and the flow speed of the soap film is generally around 2 meters per second (m / s).

[0099] The device for laser engraving on a liquid film and its optical path proposed in the embodiments of the present application are used for the process of controlling the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters, specifically: based on a signal generator, a control signal is transmitted to the laser, so that the laser emits laser according to the laser emission parameters, and the laser is controlled to focus on the liquid film through a preset lens group; based on the change in the liquid film temperature at the laser focus irradiation point on the liquid film and the change in the liquid film thickness, the engraving pattern corresponding to the laser emission parameters is engraved.

[0100] like Figure 3As shown, the device comprises a signal generator 1, a laser 2, a laser 3, a concave lens 4, a focusing convex lens 5, a flowing soap film 6, a focused irradiation point 7 of a stable pulsed laser beam on the flowing soap film 6, a series of evenly distributed pits 8 carved on the flowing soap film 6 by a focused laser beam outputting pulses at a fixed frequency and duty cycle, and a beam terminator 9. The signal generator 1 transmits a control signal to the laser 2 to control its output parameters. The laser 2 emits the laser 3 according to the received control signal. The laser 3 is focused on the flowing soap film 6 via the concave lens 4 and the focusing convex lens 5. The temperature of the soap film at the focused irradiation point 7 of the stable pulsed laser beam on the flowing soap film 6 will increase compared to the temperature at other locations on the soap film, and the local surface tension will change. That is, the surface tension at the location where the soap film is locally heated will locally decrease, thereby inducing the heat-induced Marangoni effect. The laser beam is then terminated in a beam terminator 9 having multiple heat sinks after passing through the liquid soap film 6 to avoid any danger.

[0101] In principle, the embodiments of the present application utilize the property that the elasticity of the soap film is close to zero when the surfactant concentration is in the high concentration region (the concentration of surfactant molecules is greater than its own critical micelle concentration). Specifically, in this high concentration region, the surface tension of the soap film no longer changes with the concentration of its surfactant. The definition formula of the elasticity E of the soap film is: E = -A (dσ / dA), where σ is the surface tension of the soap film and A is the surface area of ​​the studied region of the soap film. Therefore, the elasticity E of the soap film constructed using the soap solution prepared with the above-mentioned special formula is close to zero, and the propagation speed of the elastic symmetric wave in the soap film is Close to zero. Strictly speaking, the elasticity of the liquid film constructed according to the preset formula is in the range of about 0mN / m (millinewton / meter) to 0.02mN / m (millinewton / meter); taking a liquid film with a thickness of 20 microns as an example, the propagation speed of the elastic symmetric wave in the liquid film constructed according to the preset formula is in the range of about 0m / s (meter / second) to 0.05m / s (meter / second). Therefore, for the soap film that flows rapidly at a speed of about 1m / s (meter / second) to 3m / s (meter / second), the elasticity E of the soap film can be considered to be zero, and the propagation speed of the elastic symmetric wave in the soap film is about 0m / s (meter / second). can be considered to be zero. In addition, in the flowing soap film with a thickness of the micron order, the propagation speed of the symmetric Taylor wave is can be ignored, where k = 2π / λ is the wave number of the disturbance wave and λ is the wavelength of the disturbance wave.

[0102] Under this working condition, as described above, the embodiment of the present application focuses a laser beam on the soap film through a set of lens groups. A better solution is that the propagation direction of the laser beam is adjusted to be perpendicular to the soap film. At this time, the laser beam passes vertically through the soap film with a thickness of micrometers. The physical system composed of the laser and the soap film is symmetrical relative to the middle plane of the soap film, and the disturbance caused by the laser to the soap film is also a symmetrical disturbance. In addition, this method of laser heating the soap film can avoid exciting a propagation speed of 0.01 in the flowing soap film. Propagation of asymmetric Taylor waves.

[0103] In fact, since the soap film thickness is only on the micron level, if it is regarded as an idealized plane, in the embodiment of the present application, even if the propagation direction of the laser is not strictly perpendicular to the soap film, the symmetry of the overall system is still good, and the laser engraving effect on the liquid film can still be achieved. The effect of the asymmetry on the shape of the soap film (for example, the propagation of asymmetric Taylor waves) is very weak and is specifically explained here.

[0104] Below, taking the surface of a soap film as an example, the effect that can be triggered by a laser pulse (that is, the process of generating a laser engraving pattern on a liquid film in the embodiment of the present application) is specifically described from the perspective of fluid mechanics. The power of the laser output can be set to about 5 watts to 8 watts. First, the location of the soap film irradiated by the laser focus will experience a local increase in temperature compared to the location of the soap film not irradiated by the laser. According to the temperature dependence of the surface tension of the soap liquid, the surface tension of the soap film at the location heated by the laser will locally decrease compared to the surface tension of the unheated part, and a surface tension gradient caused by this temperature difference will be generated. This surface tension gradient will cause the soap liquid in the low surface tension area of ​​the soap film to be pulled to the surrounding high surface tension area of ​​the soap film, that is, the soap liquid at the heated location of the soap film is pulled to the surrounding unheated area of ​​the soap film, that is, the thermal-Marangoni effect occurs on the surface of the liquid film.

[0105] Specifically, from the symmetry discussed above, it can be seen that a pair of symmetrical pits will appear on the two surfaces of the soap film at the position where the laser is heated, that is, the thickness of the soap film at this position will be locally reduced. Because the propagation speed of the elastic symmetric wave in the soap film prepared by the above-mentioned preset formula is close to zero, the pair of pits induced on the two surfaces of the soap film by the above-mentioned focused laser heating method will not be propagated by the elastic symmetric wave, and these pits will be stable on the surface of the soap film and maintained. For a flowing soap film, these pits that are stably maintained on the surface of the soap film will also flow with the soap film. In the embodiment of the present application, liquid materials such as liquid films exhibit the same physical properties as solid materials. The embodiment of the present application thus realizes a process method for laser engraving on liquid materials such as liquid films through the above-mentioned device system.

[0106] The addition of carbon-free ink to the above-mentioned special formula is precisely to make the soap film absorb more laser energy, thereby causing the laser-irradiated part of the soap film to heat up more significantly than the unirradiated part, producing a more obvious thermally induced local surface tension gradient, thereby making the above-mentioned thermal-Marangoni effect more pronounced, thereby achieving the process effect of laser engraving on the soap film.

[0107] It should be noted that the laser engraving process on a liquid film proposed in the embodiments of the present application is to locally heat the liquid film with a laser, thereby changing the local surface tension of the heated portion of the liquid film, stimulating thermal-Marangoni flow on the surface of the liquid film, and thereby constructing a sustainable concave and uneven pattern effect on the surface of the liquid film. Based on the above-mentioned device system, technical methods and process effects, the process proposed in the embodiments of the present application is called laser engraving. However, the embodiments of the present application are completely different from actual contact engraving using a carving knife, and special emphasis and explanation are given here.

[0108] At the same time, as mentioned above, the embodiments of the present application are fundamentally different from laser engraving performed on solid materials, that is, the process of heating solid materials by laser to achieve local melting or ablation thereof, which is particularly emphasized and explained here.

[0109] This can be clearly seen from the laser power setting. Conventional laser engraving on solid materials requires the surface of the material to undergo a physical change similar to melting, requiring extremely high laser energy in a short period of time. Therefore, conventional laser engraving for solids requires laser powers of tens or even hundreds of watts. However, the laser engraving on liquid films proposed in the present embodiment essentially only requires inducing the aforementioned Marangoni flow on the surface of a liquid film with a specific formulation, thereby maintaining the concave and uneven structure generated by this Marangoni flow on the liquid film surface. The laser engraving process on liquid films thus achieved in the present embodiment does not require very high laser power. Even for liquid films flowing rapidly at speeds of approximately 1 to 3 m / s, good laser engraving effects can generally be achieved with laser power of approximately 5 to 8 watts. Furthermore, depending on actual conditions, appropriately increasing the mass fraction of carbon-free ink in the soap film solution can further reduce laser power output while achieving the same good laser engraving effect.

[0110] In addition to the above-mentioned pair of stable pits excited by a laser pulse on the two surfaces of the liquid film, based on the same process principle, the embodiment of the present application can also construct more complex engraving patterns on the liquid film.

[0111] Next, the corresponding process operation methods are introduced.

[0112] like Figure 3 and Figure 4 As shown, for a soap film 6 flowing vertically downward driven by gravity, if the output mode of laser 3 is switched to pulsed output mode, and the output frequency and output duty cycle of the pulsed laser are controlled by signal generator 1, the spatial position of laser 3 itself is kept stable. Then, after the position 7 where the flowing soap film 6 is focused and heated by the pulsed laser, a series of uniformly arranged pits 8 will follow the flow of the soap film, and the distance between the centers of each two adjacent pits is d = u / f. laser Where u is the velocity of the soap film flowing vertically downward, f laser is the output frequency of the pulse laser. laser If the frequency is higher, for example, 5000 Hz or above, the series of pits will connect to form a continuous groove. If a stable continuous output laser is used directly, then a continuous groove 18 will also be engraved after the position 17 where the flowing soap film 6 is focused and heated by the continuous output laser.

[0113] In fact, the size of the above series of pits mainly depends on the output duty cycle of the pulse laser. When the output duty cycle of the pulse laser is larger, the size of these pits is correspondingly larger; when the output duty cycle of the pulse laser is smaller, the size of these pits is correspondingly smaller.

[0114] In addition, the size of these pits is also related to the heat conduction effect on the soap film to a certain extent. This is also a unique feature of the laser engraving on liquid materials in the embodiments of the present application, which does not exist in traditional solid-state laser engraving. Specifically, because the embodiments of the present application achieve the engraving effect by stimulating Marangoni flow on the surface of the liquid film through laser heating, the size of the pattern engraved on the liquid film surface will be affected to a certain extent by the heat conduction effect in the liquid film. If the heat conduction effect in the liquid film is strong, that is, the heat from the laser heating is spread over a larger area of ​​the liquid film, then the size of the pattern engraved on the liquid film surface by the laser will also be expanded to a certain extent.

[0115] Although the effect of the laser output duty cycle on the size of the engraved pattern is stronger than the effect of the liquid film heat conduction effect, that is, changing the laser output duty cycle will have a more intuitive control on the size of the engraved pattern, the embodiment of the present application still provides a relevant solution for controlling the size of the engraved pattern from the perspective of liquid film heat conduction.

[0116] Let's take the example of engraving a pit in a liquid film. First, the laser output power can be varied. Increasing the laser output power increases the amount of heat transferred to the liquid film, resulting in a larger pit and a deeper engraving. Reducing the laser output power reduces the amount of heat transferred to the liquid film, reducing the pit's size and making the engraving shallower. Furthermore, the heat conduction effect within the liquid film can be manipulated by changing its thickness. Specifically, besides varying the flow rate, a more direct way to control the film's thickness is by changing the width of the liquid film's flow channel. In the gravity-driven soap film described above, this involves varying the distance between the two thin lines. Narrowing the soap film's flow channel increases the film's thickness at the same flow rate, enhancing the heat conduction effect. Consequently, the engraved pit, under the same laser parameters, will increase in size and deepen in depth. Conversely, increasing the width of the soap film flow channel, at the same flow rate, reduces the film thickness, weakens the heat conduction effect, and, under the same laser parameters, reduces the size and depth of the engraved pits. This demonstrates the method for controlling the size and depth of laser engraved patterns on liquid films.

[0117] As shown in Figures 5(a) and 5(b), there are schematic diagrams of several different types of laser engraving effects achieved by rapid spatial scanning of the laser. Among them, (a) is a liquid film 6 engraved by a continuous laser beam that performs rapid horizontal scanning, and a curved and continuous sinusoidal groove 22 engraved thereon, 21 is the focused irradiation point of a laser beam that performs high-speed spatial scanning on the flowing soap film 6, (b) is a liquid film 6 engraved by two laser beams that perform rapid spatial scanning, and a smiley face pattern 24 engraved thereon, 23 is the focused irradiation point of two laser beams that perform high-speed spatial scanning on the flowing liquid film 6. The two eyes in the above-mentioned smiley face pattern, that is, two elliptical pits with a diameter greater than the thickness of the laser engraving line, can be achieved by rapid scanning of the laser in the vertical and horizontal directions at the same time. Through the above ideas, the richness of the patterns of laser engraving on the liquid film in the embodiment of the present application can be further improved.

[0118] The present application also provides a method for laser engraving a liquid film using a hollow template. The process of using the hollow template to cooperate with the laser to engrave a corresponding engraving pattern on the liquid film includes: incidenting a laser on the hollow template containing the engraving pattern; after the laser is incident on the hollow area of ​​the hollow template, the laser light corresponding to the engraving image in the hollow area is incident on the liquid film to complete the engraving of the liquid film.

[0119] Specifically, as shown in Figure 5(c) and Figure 6 As shown, first, a template 28 with a hollowed-out "T" pattern can be prepared based on the desired pattern to be engraved on the liquid film, such as the letter "T." At this point, a very high-power laser pulse 27 is used, and without the aforementioned laser focusing and other operations, it is directed directly through the hollowed-out template 28. Part of the light from the high-power laser pulse 27 is blocked by the hollowed-out template 28, leaving only a high-power laser pulse 29 with a "T"-shaped pattern. This pulse irradiates the flowing soap film, forming a "T"-shaped laser pulse irradiation area 25, thereby engraving a "T"-shaped pattern 26 on the flowing soap film. Essentially, this method of laser engraving on a liquid film using a hollowed-out template is based on the same principle as the method described above using a focused laser. While the hollowed-out template method is suitable for engraving certain complex patterns, it also requires a higher-power laser because it does not rely on focused light. In addition, depending on the size of the pattern to be engraved on the liquid film, the laser can be appropriately expanded through a lens group while ensuring sufficient laser power, so that the laser passes through the designed hollow template after expansion, thereby engraving the pattern on the liquid film.

[0120] In practice, the outer contour of the template with the hollowed-out pattern can be made circular, making it easier to install directly in a standard optical frame. Furthermore, considering that the soap film is flowing at speeds of approximately 1 to 3 m / s, in order to engrave the desired pattern on the flowing soap film, the high-power laser used here only needs to output a very short pulse, and the pulse output time can be controlled according to the flow speed of the soap film. If the high-power laser output is continuous, the desired pattern cannot be engraved on the flowing soap film. Furthermore, when designing the hollowed-out pattern of the template, the horizontal shape of the hollowed-out pattern can be slightly thinner than the corresponding horizontal shape of the intended engraving pattern, while the vertical shape of the hollowed-out pattern can still be designed according to the intended engraving pattern. In this way, when the soap film flows vertically downward, the horizontal shape will be thickened due to the flow of the soap film, thereby restoring the effect of the intended engraving pattern. The specific quantitative design needs to be controlled according to the actual flow speed of the soap film.

[0121] After achieving the laser engraving effect on the liquid film, it is necessary to observe and monitor the laser engraving effect, that is, to visualize the flow of the flowing soap film 6 after laser engraving. During the engraving process, the embodiment of the present application uses interferometry and / or schlieren method to record the engraving process and engraving results of the liquid film.

[0122] Because the thickness of the flowing soap film is only on the micron scale, the depth of the laser engraving performed on it in the embodiments of the present application is also on the micron scale. Furthermore, the liquid film flows at a speed of approximately 1 to 3 meters per second. Therefore, it is difficult to observe the various laser engraved patterns on the flowing liquid film using only the human eye or ordinary photography. Therefore, the embodiments of the present application provide two main types of observation and detection methods to address different liquid film conditions.

[0123] Generally speaking, for a thin soap film (e.g., about 10 microns or less) or a relatively slow flowing soap film (e.g., about 1 m / s), the classical optical interferometry method can be used to visualize the soap film and thus reveal various patterns carved by the laser on the soap film. Figure 7As shown, the single-wavelength light source 10 and the camera 11 are placed on the same side of the flowing soap film 6 and at the same angle relative to the normal of the soap film. The single-wavelength light emitted by the single-wavelength light source 10 will be reflected on the front and back surfaces of the soap film (i.e., the gas-liquid interface) respectively. After optical interference occurs, these two parts of reflected light will be incident on the camera 11 and recorded by the photosensitive chip of the camera 11, that is, the interference fringes of the soap film are photographed. According to the relevant knowledge of wave optics, each of these interference fringes corresponds to an isopach line of the soap film, so that the various engraving patterns such as pits constructed on the soap film by the laser engraving technology of the embodiment of the present application can be visualized, and the various engraving patterns on the flowing soap film can be recorded. Generally speaking, the single-wavelength light source 10 can use a low-pressure sodium lamp with an emitted light wavelength of 589nm, or use a laser beam expansion method to irradiate the flowing liquid film with a laser.

[0124] However, it should be emphasized that when the thickness of the flowing soap film 6 is relatively thick and the flow rate is relatively high, for example, when the film thickness is approximately 40 microns or greater and the flow rate reaches approximately 3 m / s, the thickness of the soap film may vary significantly, and the interference fringes may be very dense and difficult to distinguish. In this case, the above-mentioned interferometry method is no longer suitable as a visualization method.

[0125] At this time, the classic Schlieren method can be used as a visualization method. Specifically, Figure 8As shown, the divergent light emitted by the Schlieren light source 12 is converged into parallel light by the convex lens 13, and the parallel light passes through the flowing soap film 6. Compared with the original propagation path of the parallel light, the thickness or shape disturbance on the flowing soap film 6 will cause the light to be deflected. After passing through the flow field to be measured, the above light is focused by the convex lens (Schlieren mirror) 14. At this time, a knife edge 15 is placed at the focal position. If the parallel light does not pass through the flow field to be measured, it can pass through the knife edge 15; if the parallel light passes through the flow field to be measured and is deflected by it, it will cause part of the light to pass through the knife edge 15, and part of the light will be blocked by the knife edge 15, thereby forming different light and dark areas in the Schlieren image. These areas with different light and dark reflect the characteristics of the flow field to be measured. At this time, the Schlieren image is recorded using a camera 16, and the various patterns engraved by the laser on the flowing soap film 6 are thus displayed and recorded. Through relevant optical analysis, it can be known that the Schlieren method shows the along-path integral of the first-order derivative of the refractive index, so the Schlieren method has a very high detection sensitivity. In addition, the sensitivity of the Schlieren method is also directly proportional to the focal length of the convex lens (Schlieren mirror) 14, so in actual operation, a convex lens (Schlieren mirror) 14 with a long focal length needs to be used. Through the relevant knowledge of geometric optics, it can be known that in order to ensure that the focal point of the light at the blade 15 is small enough, the focal length f1 of the convex lens 13 also needs to be correspondingly large. In order to ensure the high resolution of the image captured by the Schlieren method, the camera 16 is preferably also equipped with a telephoto lens. According to experimental experience, the focal length f1 of the convex lens 13, the focal length f2 of the convex lens (Schlieren mirror) 14, and the focal length of the lens of the camera 16 preferably need to reach about 1000 mm. The Schlieren method light source 12 can use LED light sources, sodium lamps and other light sources, and a luminous power of about 3 watts to 5 watts can achieve a good shooting effect.

[0126] It should be noted that, based on the principles of the Schlieren method, in addition to being applicable to visualizing soap films with relatively thick film thicknesses (e.g., approximately 40 microns or greater) and relatively fast flow velocities (e.g., approximately 3 m / s), the Schlieren method can also be applied to visualizing soap films with film thicknesses of approximately 10 microns or less, or flowing at a velocity of approximately 1 m / s. In other words, for soap films with film thicknesses of approximately 10 microns or less, or flowing at a velocity of approximately 1 m / s, both the interferometry and Schlieren methods can be used for visualization.

[0127] In addition, if Figure 9 As shown in FIG. 1 , there are several types of control signals transmitted to the laser for engraving the liquid film. The control signal is a voltage signal with a voltage range of 0V (volts) to 5V (volts). Figure 9The figure shows how the control signal changes over time t. When the control signal is 0V, the laser does not output; when the control signal is 5V, the laser outputs. (a) is the control signal for controlling the laser to be off, (b) is the control signal for controlling the laser to output continuously, (c) is the control signal for controlling the laser to output at a fixed frequency and duty cycle, and (d) is the control signal for customizing the distribution of engraved pits on the liquid film.

[0128] As mentioned above, in addition to a string of pits or a continuous groove engraved on the flowing liquid film when the laser is fixedly heated, and the complex patterns engraved on the flowing liquid film in conjunction with the hollow template, the process proposed in the embodiment of the present application can also engrave more abundant pattern types on the flowing liquid film by moving the heating position of the laser on the liquid film. In the above, the regulation of the laser output mode and parameters is mainly to control some basic properties of laser engraving, such as the size and depth of the engraved pits or grooves. However, the spatial position of the laser heating on the liquid film has not changed, that is, the propagation path of the laser itself has not changed. As mentioned above, in order to engrave more abundant patterns on the liquid film, the position where the laser is focused and heated on the liquid film also needs to be controlled.

[0129] As mentioned above, the embodiments of the present application provide two types of schemes for moving the laser heating position on the liquid film, which are described in more detail herein. First, a mechanical multi-axis control method is used to control the movement of the laser emitter head at different spatial positions, thereby realizing laser engraving at different positions of the liquid film, and then cooperating with the numerical control system to engrave various different patterns on the liquid film. However, for the above-mentioned soap film flowing at a speed of about 1 m / s to 3 m / s, this mechanical control method is not easy to engrave the expected complex pattern on the soap film. Because the mechanical movement of the laser emitter head is usually much slower than the flow of the soap film driven by gravity, it is easy for the actual engraved pattern on the soap film to be deformed compared to the expected style. It may even be limited by the upper limit of the scanning speed of the above-mentioned optical scanning system, resulting in some patterns being unable to be engraved on the flowing soap film.

[0130] In comparison, there is another type of method that can achieve high-speed laser scanning, that is, using a high-speed scanning mirror or a galvanometer to reflect the laser and irradiate the reflected laser on the liquid film. This type of method essentially changes the direction of laser propagation, that is, the angle. As mentioned above, in the embodiment of the present application, since the thickness of the soap film is only on the order of microns, changing the incident direction of the laser relative to the soap film does not affect the process effect of the laser engraving in the embodiment of the present application. Through the relationship of trigonometric functions, it can be seen that the greater the distance between the above-mentioned high-speed scanning mirror or galvanometer and the soap film, the faster the movement speed of the laser irradiated point on the soap film will be. Since the scanning frequency of the high-speed scanning mirror or galvanometer can usually reach several thousand hertz or even higher, this type of method can be used for laser engraving on a flowing soap film. In addition, a scanning system composed of multiple sets of high-speed scanning mirrors or galvanometers with different axes can achieve high-speed scanning of the laser in multiple degrees of freedom directions, and thus can achieve engraving of various complex patterns on the plane of the entire soap film.

[0131] It's worth noting that, in practice, if one still wants to achieve the effect of rapidly scanning a laser engraving on a liquid film without the aforementioned mechanical multi-axis control system and high-speed scanning mirror or galvanometer system, the present application provides a simple method using a rapidly vibrating tuning fork or other vibrating device. Specifically, an optical reflector can be mounted on the end of the tuning fork, allowing the laser to be reflected by the reflector into a focusing lens system, focusing and heating the liquid film to achieve the laser engraving effect. Since the natural vibration frequency of a vibrating device such as a tuning fork can reach hundreds of hertz, the spatial vibration frequency of the laser reflected by the reflector after striking the tuning fork is the natural vibration frequency of the tuning fork. Consequently, the flowing soap film is engraved with a rich pattern by the rapidly spatially scanning laser. For example, when the oscillating laser vibrates horizontally, a sinusoidal groove with an amplitude that decays over time is engraved on the flowing soap film. This precisely reflects the amplitude decay of the tuning fork over time after being struck. Overall, this is an economical, simple, and easily implemented method for rapid spatial laser scanning and simultaneous laser engraving of liquid films. Furthermore, this method allows the tiny mechanical vibrations of vibrating devices such as tuning forks to be amplified by the optical path and recorded on the flowing soap film. In this case, the flowing soap film acts like the paper tape used in an electrocardiogram or a seismic recorder. This approach could be explored in future research and applications in mechanical vibration recording and other areas.

[0132] Corresponding to the aforementioned liquid film laser engraving method, the present application also provides a liquid film laser engraving device. Since the device embodiment of the present application corresponds to the aforementioned method embodiment, details not disclosed in the device embodiment can be referred to the aforementioned method embodiment and will not be further described in the present application.

[0133] Figure 10 A schematic diagram of a structure of a device for laser engraving on a liquid film provided in an embodiment of the present disclosure, such as Figure 10 As shown, including:

[0134] a construction unit 21 for constructing a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero, so that the thickness variation applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by the fluctuations in the liquid;

[0135] The setting unit 22 is used to set the laser emission parameters according to the pattern information to be engraved on the liquid film surface. Different engraving pattern requirements correspond to different laser emission parameters.

[0136] The engraving unit 23 is used to control the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters.

[0137] The present invention provides a liquid film laser engraving device that constructs a liquid film according to a preset recipe. The liquid film has near-zero elasticity, allowing thickness variations applied to the film to remain on the surface and not be propagated by fluctuations in the liquid. Laser emission parameters are then set based on the desired pattern to be engraved on the liquid film surface. Different laser emission parameters correspond to different engraving pattern requirements, and the laser is controlled to engrave the corresponding pattern on the liquid film based on these laser emission parameters. Based on the constructed liquid film with near-zero elasticity, the laser is controlled to complete the engraving on the liquid film, thus filling the current theoretical and technical gaps in laser engraving on liquid films.

[0138] Furthermore, in a possible implementation of this embodiment, as Figure 11 As shown, when the liquid film is a soap film, the construction unit 21 includes:

[0139] The configuration module 211 is used to prepare the liquid film according to the preset formula, wherein the preset formula is that the concentration of the surfactant molecules is greater than the critical micelle concentration of the surfactant molecules.

[0140] The construction module 212 is used to draw the liquid film based on a preset liquid film manufacturing device to form a liquid film at a preset flow speed.

[0141] Furthermore, in a possible implementation of this embodiment, the mass fraction of glycerol in the preset formula is 8%-12%, the mass fraction of carbonless ink is 2%, the concentration of surfactant molecules needs to be 4-6 times their own critical micelle concentration, and the rest of the soap solution is deionized water.

[0142] Furthermore, in a possible implementation of this embodiment, as Figure 11As shown, the engraving unit 23 is also used for:

[0143] Transmitting a control signal to the laser based on the signal generator, so that the laser emits laser light according to the laser emission parameters;

[0144] The laser is controlled to focus on the liquid film through a preset lens group, and the position where the laser heats the liquid film can change over time;

[0145] Laser heating is used to create a local gradient in the surface tension of the liquid film, which stimulates thermally induced Marangoni flow on the liquid film surface and creates a change in the thickness of the liquid film.

[0146] An engraving pattern corresponding to the laser emission parameters is engraved on the liquid film.

[0147] Furthermore, in a possible implementation of this embodiment, as Figure 11 As shown, the device also includes:

[0148] The processing unit 24 is configured to inject the laser light into the beam terminator after the laser light passes through the liquid film.

[0149] Furthermore, in a possible implementation of this embodiment, as Figure 11 As shown, the engraving unit 23 is also used for:

[0150] The laser is incident on a hollow template containing an engraved pattern;

[0151] After the laser is incident on the hollow area of ​​the hollow template, the laser light of the engraved image corresponding to the hollow area is incident on the liquid film to complete the engraving of the liquid film.

[0152] Furthermore, in a possible implementation of this embodiment, as Figure 11 As shown, the device also includes:

[0153] The recording unit 25 is used to observe and record the engraving process and results of the liquid film by using the interference method and / or the schlieren method during the engraving process.

[0154] It should be noted that the above explanation of the method embodiment is also applicable to the device of this embodiment, and the principles are the same, which is not limited in this embodiment.

[0155] According to an embodiment of the present disclosure, the present disclosure also provides an electronic device, a readable storage medium, and a computer program product.

[0156] Figure 12A schematic block diagram of an example electronic device 300 that can be used to implement embodiments of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are provided as examples only and are not intended to limit the implementation of the present disclosure described and / or claimed herein.

[0157] like Figure 12 As shown, the device 300 includes a computing unit 301, which can perform various appropriate actions and processes according to a computer program stored in a ROM (Read-Only Memory) 302 or a computer program loaded from a storage unit 308 into a RAM (Random Access Memory) 303. Various programs and data required for the operation of the device 300 can also be stored in the RAM 303. The computing unit 301, ROM 302, and RAM 303 are connected to each other via a bus 304. An I / O (Input / Output) interface 305 is also connected to the bus 304.

[0158] Various components in device 300 are connected to I / O interface 305, including: an input unit 306, such as a keyboard, mouse, etc.; an output unit 307, such as various types of displays, speakers, etc.; a storage unit 308, such as a magnetic disk, optical disk, etc.; and a communication unit 309, such as a network card, modem, wireless communication transceiver, etc. The communication unit 309 allows device 300 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0159] The computing unit 301 can be a variety of general-purpose and / or specialized processing components with processing and computing capabilities. Some examples of the computing unit 301 include, but are not limited to, a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), various specialized AI (Artificial Intelligence) computing chips, various computing units that run machine learning model algorithms, a DSP (Digital Signal Processor), and any suitable processor, controller, microcontroller, etc. The computing unit 301 performs the various methods and processes described above, such as the method for laser engraving on a liquid film. For example, in some embodiments, the method for laser engraving on a liquid film can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 308. In some embodiments, part or all of the computer program can be loaded and / or installed on the device 300 via the ROM 302 and / or the communication unit 309. When the computer program is loaded into the RAM 303 and executed by the computing unit 301, one or more steps of the method described above can be performed. Alternatively, in other embodiments, the computing unit 301 may be configured to execute the aforementioned method of laser engraving on a liquid film in any other appropriate manner (for example, by means of firmware).

[0160] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, FPGAs (Field Programmable Gate Arrays), ASICs (Application-Specific Integrated Circuits), ASSPs (Application-Specific Standard Products), SOCs (System on Chips), CPLDs (Complex Programmable Logic Devices), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special-purpose or general-purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0161] The program code for implementing the method of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that when the program code is executed by the processor or controller, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0162] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus, or any suitable combination of the foregoing. More specific examples of machine-readable storage media may include an electrical connection based on one or more wires, a portable computer disk, a hard disk, RAM, ROM, EPROM (Electrically Programmable Read-Only-Memory) or flash memory, optical fiber, CD-ROM (Compact Disc Read-Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0163] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (Cathode-Ray Tube) or LCD (Liquid Crystal Display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0164] The systems and techniques described herein can be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: LAN (Local Area Network), WAN (Wide Area Network), the Internet, and blockchain networks.

[0165] A computer system may include a client and a server. The client and server are generally remote from each other and typically interact via a communication network. This client-server relationship is established by computer programs running on the respective computers, establishing a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host, a host product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and VPS services ("Virtual Private Servers" or simply "VPS"). The server may also be a server in a distributed system or a server integrated with blockchain.

[0166] It's important to note that artificial intelligence (AI) is the study of how computers can simulate certain human thought processes and intelligent behaviors (such as learning, reasoning, thinking, and planning). This encompasses both hardware and software technologies. AI hardware technologies generally include sensors, specialized AI chips, cloud computing, distributed storage, and big data processing. AI software technologies primarily encompass computer vision, speech recognition, natural language processing, machine learning / deep learning, big data processing, and knowledge graphs.

[0167] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not a limitation herein.

[0168] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

[0169] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

Claims

1. A method for laser engraving on a liquid film, characterized in that: include: constructing a liquid film according to a preset formula, wherein the elasticity of the liquid film is close to zero; According to the pattern information that needs to be engraved on the liquid film surface, the laser emission parameters are set. Different engraving pattern requirements correspond to different laser emission parameters. Controlling the laser to carve a corresponding engraving pattern on the liquid film according to the laser emission parameters; Wherein, the liquid film is a soap film, and the step of constructing the liquid film according to a preset formula includes: Prepare a liquid film according to the preset formula, wherein the preset formula is a concentration of surfactant molecules greater than the critical micelle concentration of the surfactant molecules, and the preset formula includes carbonless ink, which is used to increase the absorption of laser energy by the soap film; Drawing the liquid film based on a preset liquid film manufacturing device to form a liquid film at a preset flow rate; wherein the engraved pattern is stably maintained on the surface of the liquid film relative to the flowing liquid film; Among them, the mass fraction of glycerol in the preset formula is 8%-12%, the mass fraction of carbonless ink is 2%, the concentration of surfactant molecules needs to be 4-6 times its own critical micelle concentration, and the rest of the soap solution is deionized water.

2. The method according to claim 1, characterized in that The step of controlling the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters comprises: Transmitting a control signal to the laser based on the signal generator, so that the laser emits laser light according to the laser emission parameters; The laser is controlled to focus on the liquid film through a preset lens group, and the position where the laser heats the liquid film can change over time; Laser heating is used to create a local gradient in the surface tension of the liquid film, which stimulates thermally induced Marangoni flow on the liquid film surface and creates a change in the thickness of the liquid film. An engraving pattern corresponding to the laser emission parameters is engraved on the liquid film.

3. The method according to claim 2, characterized in that The method further comprises: After the laser light passes through the liquid film, it enters the beam stopper.

4. The method according to claim 1, wherein The step of controlling the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters comprises: The laser is incident on a hollow template containing an engraved pattern; After the laser is incident on the hollow area of ​​the hollow template, the laser light of the engraved image corresponding to the hollow area is incident on the liquid film to complete the engraving of the liquid film.

5. The method according to claim 1, characterized in that The method further comprises: During the engraving process, the interferometry method and / or the Schlieren method are used to observe and record the engraving process and results of the liquid film.

6. A device for laser engraving on a liquid film, characterized in that: include: a construction unit, configured to construct a liquid film according to a preset recipe, wherein the elasticity of the liquid film is close to zero, so that thickness variations applied to the liquid film can be maintained on the surface of the liquid film and will not be propagated by fluctuations in the liquid; A setting unit is used to set the laser emission parameters according to the pattern information to be engraved on the liquid film surface. Different engraving pattern requirement information corresponds to different laser emission parameters. An engraving unit, configured to control the laser to engrave a corresponding engraving pattern on the liquid film according to the laser emission parameters; Wherein, the liquid film is a soap film, and the structural unit comprises: a configuration module, configured to prepare a liquid film according to the preset formula, wherein the preset formula is such that the concentration of surfactant molecules is greater than the critical micelle concentration of the surfactant molecules, and the preset formula includes carbonless ink, which is used to increase the absorption of laser energy by the soap film; A construction module is used to draw the liquid film based on a preset liquid film manufacturing device to form a liquid film at a preset flow rate; wherein the engraved pattern is stably maintained on the surface of the liquid film relative to the flowing liquid film; Among them, the mass fraction of glycerol in the preset formula is 8%-12%, the mass fraction of carbonless ink is 2%, the concentration of surfactant molecules needs to be 4-6 times its own critical micelle concentration, and the rest of the soap solution is deionized water.

7. The device according to claim 6, characterized in that The engraving unit is also used for: Transmitting a control signal to the laser based on the signal generator, so that the laser emits laser light according to the laser emission parameters; The laser is controlled to focus on the liquid film through a preset lens group, and the position where the laser heats the liquid film can change over time; Laser heating is used to create a local gradient in the surface tension of the liquid film, which stimulates thermally induced Marangoni flow on the liquid film surface and creates a change in the thickness of the liquid film. An engraving pattern corresponding to the laser emission parameters is engraved on the liquid film.

8. The device according to claim 7, characterized in that The device further comprises: The processing unit is used for injecting the laser light into the beam terminator after the laser light passes through the liquid film.

9. The device according to claim 6, characterized in that The engraving unit is also used for: The laser is incident on a hollow template containing an engraved pattern; After the laser is incident on the hollow area of ​​the hollow template, the laser light of the engraved image corresponding to the hollow area is incident on the liquid film to complete the engraving of the liquid film.

10. The device according to claim 6, characterized in that The device further comprises: The recording unit is used to observe and record the engraving process and results of the liquid film by using an interference method and / or a schlieren method during the engraving process.

11. An electronic device, characterized in that: include: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 5.

12. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to cause the computer to execute the method according to any one of claims 1 to 5.

13. A computer program product, characterized in that The invention comprises a computer program which, when executed by a processor, implements the method according to any one of claims 1 to 6.

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