Based on handheld laser cleaning dynamic focusing output device

Abstract

This disclosure relates to a handheld laser cleaning dynamic focusing output device, belonging to the field of laser cleaning technology. The handheld laser cleaning dynamic focusing output device includes a laser emitting module, a distance detection module, a beam combining module, a focusing module, and a focal length adjustment module. The distance detection module is configured to emit a probe beam towards the target workpiece and acquire real-time distance information between the handheld laser cleaning dynamic focusing output device and the target workpiece based on the reflection signal of the probe beam. The beam combining module enables the laser beam and the probe beam to propagate collinearly along the same principal optical axis. The focusing module is used to focus the laser beam and the probe beam together on the same working area of ​​the target workpiece. The focal length adjustment module is configured to dynamically adjust the effective focal length of the system according to the real-time distance information detected by the distance detection module, so that the laser beam is always focused on the surface of the target workpiece. The device provided in this application can achieve automatic focusing.

Description

Technical Field

[0001] This invention relates to the field of laser cleaning technology, and in particular to a handheld laser cleaning dynamic focusing output device. Background Technology

[0002] A laser cleaner is an advanced piece of equipment that uses a high-energy pulsed laser beam to perform non-contact cleaning of workpiece surfaces. Its working principle is as follows: within an extremely short time (typically nanoseconds to picoseconds), a high-energy-density laser acts on surface contaminants (such as oil, rust, paint, oxides, etc.), causing them to rapidly heat up and vaporize, undergo plasma explosion, or directly sublimate, thereby peeling them off from the substrate and achieving a highly efficient and clean removal effect.

[0003] However, most handheld laser cleaning equipment currently on the market still uses a fixed-focus optical system, which cannot dynamically adjust the focus position according to the surface morphology of the workpiece. During operation, if it is necessary to change the working distance (such as cleaning curved surfaces, steps, or uneven surfaces), it often relies on manual focusing, which is not only inefficient, but also prone to deviation from the optimal cleaning position due to differences in operator experience. This can lead to problems such as incomplete cleaning, substrate damage, or energy waste, seriously affecting cleaning quality and process stability. Summary of the Invention

[0004] The purpose of this application is to provide a handheld laser cleaning dynamic focusing output device that can automatically adjust the focus so that the laser beam is always focused on the surface of the target workpiece, thereby improving laser efficiency and quality.

[0005] To address the aforementioned technical problems, this application provides the following technical solutions:

[0006] This application provides a handheld laser cleaning dynamic focusing output device, comprising:

[0007] The laser emitting module is used to output a laser beam;

[0008] The distance detection module is configured to emit a probe beam toward the target workpiece and obtain real-time distance information between the handheld laser cleaning dynamic focusing output device and the target workpiece based on the reflection signal of the probe beam.

[0009] The beam combining module is located at the intersection of the output optical paths of the laser emitting module and the distance detection module. The beam combining module is configured to have different optical response characteristics to the laser beam and the probe beam, so that the laser beam and the probe beam propagate collinearly along the same principal optical axis after being combined.

[0010] The focusing module, located in the downstream optical path of the beam combining module, is used to focus the laser beam and the probe beam together onto the same working area of ​​the target workpiece.

[0011] The focal length adjustment module is at least partially disposed in the optical path between the laser emission module and the beam combining module. The focal length adjustment module is communicatively connected to the distance detection module and is configured to dynamically adjust the effective focal length of the system according to the real-time distance information detected by the distance detection module, so that the laser beam is always focused on the surface of the target workpiece.

[0012] In some modified embodiments of this application, it also includes:

[0013] The galvanometer module, located between the beam combining module and the focusing module, is used to receive the collinear beam after the laser beam and the probe beam are combined, and to deflect it in at least one dimension according to the control command, so as to drive the focused spot of the collinear beam to scan the surface of the target workpiece according to a preset trajectory, thereby realizing regional cleaning operation.

[0014] In some modified embodiments of this application, the beam combining module is configured to exhibit transmission characteristics for a first wavelength laser beam and reflection characteristics for a second wavelength probe beam, so that the laser beam and the probe beam propagate collinearly along the same principal optical axis.

[0015] In some modified embodiments of this application, the bundle-combining module includes:

[0016] Optical substrate, tilted;

[0017] An antireflective coating is disposed on the side facing the laser emitting module. The antireflective coating exhibits transmission characteristics to the first wavelength laser beam.

[0018] A reflective film is disposed on the side facing the distance detection module, and the reflective film exhibits reflective properties to the detection beam of the second wavelength.

[0019] In some modified embodiments of this application, the transmittance of the antireflective coating to a laser beam of the first wavelength is greater than or equal to 99.5%;

[0020] And / or, the reflectivity of the reflective film to the probe beam of the second wavelength is greater than or equal to 98%.

[0021] In some modified embodiments of this application, the focus adjustment module includes:

[0022] A focusing lens is positioned in the optical path between the laser emitting module and the beam combining module;

[0023] The guide rail extends along the laser emission direction of the laser emission module, and the focusing lens is slidably connected to the guide rail;

[0024] The drive mechanism is connected to the focusing lens and is used to drive the focusing lens to slide along the guide rail to adjust the effective focal length of the system so that the laser beam is always focused on the surface of the target workpiece.

[0025] In some modified embodiments of this application, a limit structure is provided on the guide rail to limit the position of the focusing lens so that the focusing lens can move within a set range.

[0026] In some modified embodiments of this application, the focusing module has an anti-focus point, so that the detection light reflected from the surface of the target workpiece can be transmitted in reverse along the original optical path and returned to the distance detection module via the beam combining module;

[0027] The distance detection module is a time-of-flight ranging sensor with coaxial transmission and reception capabilities. The emitted detection light and the receiving field of view share the same optical axis, so that part of the detection light reflected by the workpiece can return to the receiving unit of the distance detection module along the original path.

[0028] In some modified embodiments of this application, it also includes:

[0029] The control module is communicatively connected to both the distance detection module and the focus adjustment module.

[0030] The control module is configured to receive real-time distance information output by the distance detection module; determine the corresponding target focusing position based on the real-time distance information, generate the corresponding focal length adjustment command; and send the focal length adjustment command to the focal length adjustment module to drive it to dynamically adjust the optical focusing position so that the effective focal length of the system matches the target focusing position, thereby ensuring that the laser beam is always accurately focused on the surface of the target workpiece.

[0031] In some modified embodiments of this application, the control module is communicatively connected to the laser emitting module. The control module is configured to compare the real-time distance information output by the distance detection module with a preset safe working distance threshold. When the real-time distance information is greater than the safe working distance threshold, the control module generates a laser disable command and sends it to the laser emitting module to control it to stop outputting the laser beam.

[0032] Compared to existing technologies, the handheld laser cleaning dynamic focusing output device provided in this application combines the laser beam and the probe beam through a beam combining module, allowing them to propagate collinearly along the same principal optical axis. A focusing module then focuses both beams onto the same target workpiece area. This enables the distance detection module to detect the axial distance between the laser cleaning head and the laser action position on the target workpiece surface in real time. Furthermore, the focus adjustment module adjusts the system's effective focal length in real time, ensuring the laser beam remains focused on the target workpiece surface, thus achieving automatic focusing. This improves cleaning efficiency and avoids issues such as incomplete cleaning, substrate damage, or energy waste caused by operator experience differences leading to focal deviation from the optimal cleaning position. Ultimately, this enhances cleaning quality and process stability. Attached Figure Description

[0033] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein:

[0034] Figure 1 A schematic diagram of a handheld laser cleaning dynamic focusing output device is shown.

[0035] Figure 2 A schematic diagram of a partial structure of a handheld laser cleaning dynamic focusing output device is shown.

[0036] Figure 3 A schematic diagram illustrates a method for calculating the effective focal length of a system based on a handheld laser cleaning dynamic focusing output device.

[0037] Explanation of icon numbers:

[0038] 1. Laser emitting module; 2. Drive mechanism; 3. Guide rail; 4. Focusing lens; 5. Beam combining module; 6. Distance detection module; 7. Galvanometer module; 8. Focusing module; 9. Control module. Detailed Implementation

[0039] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0040] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains.

[0041] A laser cleaner is an advanced piece of equipment that uses a high-energy pulsed laser beam to perform non-contact cleaning of workpiece surfaces. Its working principle is as follows: within an extremely short time (typically nanoseconds to picoseconds), a high-energy-density laser acts on surface contaminants (such as oil, rust, paint, oxides, etc.), causing them to rapidly heat up and vaporize, undergo plasma explosion, or directly sublimate, thereby peeling them off from the substrate and achieving a highly efficient and clean removal effect.

[0042] However, most handheld laser cleaning equipment currently on the market still uses a fixed-focus optical system, which cannot dynamically adjust the focus position according to the surface morphology of the workpiece. During operation, if it is necessary to change the working distance (such as cleaning curved surfaces, steps, or uneven surfaces), it often relies on manual focusing, which is not only inefficient, but also prone to deviation from the optimal cleaning position due to differences in operator experience. This can lead to problems such as incomplete cleaning, substrate damage, or energy waste, seriously affecting cleaning quality and process stability.

[0043] To address the aforementioned technical problems, the handheld laser cleaning dynamic focusing output device provided in this application embodiment can achieve automatic focusing, ensuring that the laser beam is always focused on the surface of the target workpiece, thereby improving laser efficiency and quality.

[0044] like Figure 1 As shown, a handheld laser cleaning dynamic focusing output device includes a laser emitting module 1, a distance detection module 6, a beam combining module 5, a focusing module 8, and a focal length adjustment module. The laser emitting module 1 is used to output a laser beam. The distance detection module 6 is configured to emit a probe beam towards the target workpiece and obtain real-time distance information between the handheld laser cleaning dynamic focusing output device and the target workpiece based on the reflection signal of the probe beam. The beam combining module 5 is located in the intersection area of ​​the output optical paths of the laser emitting module 1 and the distance detection module 6. The beam combining module 5 is configured to have different optical response characteristics to the laser beam and the probe beam, so that the laser beam and the probe beam propagate collinearly along the same principal optical axis after beam combining. The focusing module 8 is located in the downstream optical path of the beam combining module 5 and is used to focus the laser beam and the probe beam together on the same action area of ​​the target workpiece. The focal length adjustment module is at least partially located in the optical path between the laser emitting module 1 and the beam combining module 5. The focal length adjustment module is communicatively connected to the distance detection module 6 and is configured to dynamically adjust the effective focal length of the system according to the real-time distance information detected by the distance detection module 6, so that the laser beam is always focused on the surface of the target workpiece.

[0045] Laser emitting module 1 refers to an integrated optical-electrical unit used to generate and output a high-energy-density pulsed laser beam. Its output beam wavelength, pulse width, repetition frequency, and peak power are adapted to the thermodynamic removal mechanism of surface contaminants, enabling selective removal of deposits such as rust, paint, oil, and oxide layers. Laser emitting module 1 can be a fiber laser, offering high beam quality, high efficiency, compact structure, and maintenance-free operation, suitable for industrial handheld or automated cleaning (the most mainstream approach). Laser emitting module 1 can also be a solid-state laser, with high peak power, large size, and water cooling requirements, suitable for aerospace and thick rust layer cleaning. Laser emitting module 1 can also be a disk laser, with high average power and good heat dissipation, suitable for large-area, high-speed cleaning. Laser emitting module 1 can also be a green or ultraviolet laser (frequency doubling), with high photon energy, suitable for non-metallic or precision cleaning. The parameters of the laser excitation module can be designed to adapt to cleaning needs in various scenarios. For handheld lightweight cleaning scenarios, a fiber laser with an output power of 100W-200W can be used, with a wavelength of 1064nm±4nm or 1080nm±10nm, a pulse width of 80ns-160ns (which can be extended to an adjustable range of 2ns-500ns according to the cleaning accuracy requirements), a power adjustment range of 5%-100%, and a beam quality M² < 1.3-1.7. It can be equipped with an air-cooling system to achieve efficient heat dissipation. Through the above parameter combination, precise and efficient cleaning under different working conditions can be achieved.

[0046] The distance detection module 6 is a photoelectric sensing unit used for non-contact measurement of the axial distance between the laser cleaning head and the target workpiece surface. It emits a probe beam and receives its reflected echo, outputting an electrical signal characterizing the current working distance based on the time-of-flight method, providing feedback for dynamic focus adjustment. The distance detection module 6 can have a built-in red light generator with a wavelength of 630-670nm. Red light (probe light) has strong penetrating power and strong anti-interference capabilities. The red light generator emits red light towards a 45° reflecting mirror (beam combining module 5), which passes through a galvanometer (if present) and a focusing lens group (focusing module) to reach the surface to be cleaned (target workpiece surface). The surface to be cleaned reflects the red light. Because the focusing lens group has an anti-focal point, the reflected red light returns to the red light displacement sensor through the focusing lens group, galvanometer, and 45° reflecting mirror. The reflected red light is received by the photodetector within the sensor. In some embodiments, the photodetector can be a CMOS image sensor array (complementary metal-oxide-semiconductor image sensor array). The red light indicator displacement sensor uses the time-of-flight method to measure the time difference between the emission and reception of red light. This time difference is combined with the speed of light to calculate the distance between the sensor and the target, thus obtaining the displacement change. For example, the distance detection module 6 can use the Mi-Iridium ILD1750 series, with a measurement range covering 2mm–750mm, offering ultra-high measurement accuracy, a maximum permissible error of 0.06% of full scale, a minimum repeatability accuracy of 0.1μm, and a maximum measurement frequency of 7.5kHz.

[0047] To ensure measurement accuracy, the red light displacement sensor is calibrated before use. This is because the optical path of the red light emitted by the sensor, passing through a 45° reflecting mirror, a galvanometer (if applicable), and a focusing lens group, is different at each point on the surface to be cleaned. Therefore, the distance measured by the red light displacement sensor varies. During calibration, the distance data from the red light displacement sensor to each point can be measured at the focal length (focusing module) of the focusing lens group and recorded as a reference value. This data is then transmitted to the control system (control module 9). When the distance data on the working surface changes, the control system quickly calculates the corresponding effective focal length value by comparing it with the reference value and transmits the signal to the miniature piezoelectric ceramic motor (drive mechanism 2). For example, before the equipment is activated, a mapping relationship between the output value of the distance detection module 6 and the actual surface position of the workpiece can be obtained through multi-point distance calibration and stored in the control module 9. During operation, the control module 9 can convert the real-time distance measurement result into the desired laser focus position based on the mapping relationship and drive the focal length adjustment module to dynamically adjust the axial position of the focusing lens to maintain the laser beam always focused on the workpiece surface.

[0048] The beam combiner module 5 refers to a wavelength-selective optical component used to combine and propagate at least two beams of different wavelengths (e.g., a high-energy laser for cleaning and a probe beam for ranging) along the same principal optical axis. Based on the differences in the response of different wavelengths to the optical interface, it achieves directional guidance with high transmission and high reflection, thereby ensuring that the multiple beams act confocally on the same area of ​​the target workpiece. The beam combiner module 5 can be a dichroic beam combiner mirror, equipped with a flat glass substrate, with single-sided or double-sided coating. It utilizes the interference effect of dielectric films to achieve wavelength selectivity, and features a simple structure, low cost, and high damage threshold.

[0049] The focusing module 8 is an optical component located downstream of the beam combining optical path, used to converge the incident laser beam and the probe beam onto the surface of the target workpiece. The focusing module 8 can be a fixed-focal-length focusing lens, such as a single lens or a cemented doublet lens (e.g., plano-convex, biconvex). The focusing module 8 can employ a dual-lens combination design and is equipped with an anti-focus point to ensure that the red light passing through the focusing lens group can return along the focusing lens group to the red light displacement sensor. The overall weight of the focusing module 8 can be controlled to within 150g, meeting the requirements for handheld portability. For example, the focusing module 8 may include a plano-convex fused silica lens with broadband anti-reflection coatings for 1064 nm and 635 nm on both surfaces.

[0050] The focus adjustment module is an electromechanical integrated actuator located in the optical path between the laser emitting module 1 and the focusing module 8. It dynamically adjusts the optical focusing position based on external ranging signals. Through the drive mechanism 2, it moves the adjustable focusing optical components along the optical axis, thereby changing the convergence point of the laser beam and ensuring the focal point always coincides with the surface of the target workpiece. The focus adjustment module can dynamically focus, compensating for changes in workpiece height, surface undulations, or hand-held shaking. It also ensures the laser is always in a minimum spot size state, improving cleaning efficiency. The focus adjustment module can be directly connected to the focusing module to adjust the effective focal length, or it can adjust the effective focal length by adjusting other lenses (such as a focusing lens).

[0051] The focus adjustment module can be a piezoelectric ceramic driven structure. Piezoelectric materials undergo nanoscale expansion and contraction under voltage, resulting in fast response, high resolution, and no magnetic interference; suitable for high-precision fine-tuning, such as precision cleaning and semiconductor repair. The focus adjustment module can also consist of a stepper or servo motor with a lead screw and guide rail 3. The motor rotation converts the lead screw into linear motion; it offers large stroke, strong thrust, and low cost, suitable for large equipment and low-speed, high-load scenarios. The focus adjustment module can also be a voice coil motor driven structure, similar to a loudspeaker, where an energized coil moves under the force of a magnetic field; it offers high speed, good linearity, and long lifespan, suitable for mainstream industrial solutions, balancing speed and stroke. The focus adjustment module includes an adjustable focusing optical component and a drive mechanism 2 connected to it. The drive mechanism 2 is configured to drive the adjustable focusing optical component to move along the optical axis according to the adjustment command output by the control module 9, dynamically changing the axial position of the laser focus. The drive mechanism 2 can be a voice coil motor, with its mover rigidly connected to the focusing lens (adjustable focusing optical component), a stroke range of ±3mm, and a repeatability of ±1μm.

[0052] The effective focal length of the system does not refer to the physical focal length of a single lens, but rather to the equivalent focusing distance of the entire optical path from the laser emitter to the workpiece surface. In other words, it is the distance from the point where the laser beam actually converges to its smallest spot (focal point) to a reference surface (such as the end face of the laser emitter). When the focal length adjustment module moves the focusing lens, it changes the beam convergence angle of the entire system, causing the focal point position to move back and forth along the optical axis. This variable distance from the focal point to the workpiece is achieved by adjusting the effective focal length of the system. Adjusting the effective focal length to a preset distance means moving the focal point of the laser beam from the current depth to a position corresponding to the preset target working distance by driving the focal length adjustment module (e.g., moving the focusing lens 4), thus ensuring that the focal point always falls on the surface of the workpiece regardless of its height.

[0053] Compared to existing technologies, the handheld laser cleaning dynamic focusing output device provided in this application combines the laser beam and the probe beam through the beam combining module 5, and then propagates them collinearly along the same principal optical axis. The focusing module 8 focuses both beams onto the same working area of ​​the target workpiece. This allows the distance detection module 6 to detect the axial distance between the laser cleaning head and the surface of the target workpiece (the laser action position) in real time. The focal length adjustment module adjusts the effective focal length of the system based on this distance, ensuring that the laser beam is always focused on the surface of the target workpiece. This achieves automatic focusing, thereby improving cleaning efficiency and avoiding problems such as incomplete cleaning, substrate damage, or energy waste caused by differences in operator experience. This improves cleaning quality and process stability.

[0054] like Figure 1 and Figure 2As shown, in some modified embodiments of this application, a galvanometer module 7 is also included, located between the beam combining module 5 and the focusing module 8. It is used to receive the collinear beam after the laser beam and the probe beam are combined, and to deflect it in at least one dimension according to the control command, so as to drive the focused spot of the collinear beam to scan the surface of the target workpiece according to a preset trajectory, thereby realizing regional cleaning operation.

[0055] The galvanometer module 7 refers to the high-speed beam deflection unit located between the beam combining module 5 and the focusing module 8. It includes at least one rotatable mirror and corresponding drive and feedback mechanisms. The galvanometer module 7 is configured to receive collinearly propagating laser beams and probe beams, and dynamically deflects in a single-axis or dual-axis direction according to control commands to guide the focused spot to perform a two-dimensional scan on the target workpiece surface along a preset trajectory, thereby achieving regionalized laser cleaning operations. The galvanometer module 7 can be a single-axis galvanometer, consisting of one mirror and one drive system, scanning only in one direction (X or Y), suitable for linear cleaning (such as weld rust removal) and simple reciprocating motion. The galvanometer module 7 can also be a dual-axis galvanometer, including two orthogonally mounted mirrors (e.g., X-axis in front, Y-axis behind), achieving arbitrary planar trajectories through the coordinated deflection of the two mirrors. The galvanometer module 7 may include at least one deflectable mirror and a servo drive mechanism 2 connected thereto. The deflectable mirror is configured to receive the collinear beam after beam combining and to be deflected in a controlled manner in at least one dimension according to the scanning command output by the control module 9, so that the light spot converged by the focusing module 8 forms a predetermined cleaning trajectory on the surface of the target workpiece.

[0056] In some modified embodiments of this application, the beam combining module 5 is configured to exhibit transmission characteristics for a first wavelength laser beam and reflection characteristics for a second wavelength probe beam, so that the laser beam and the probe beam propagate collinearly along the same principal optical axis.

[0057] The laser (e.g., 1064nm) travels along the principal optical axis after passing through the beam combiner, while the probe light (e.g., 635nm red light) is reflected and refracted onto the same principal optical axis. The two beams completely overlap at the beam combiner point, becoming collinear beams. This collinear beam is then focused onto the same point on the workpiece by the subsequent focusing module 8, ensuring that the target area is precisely where it is hit, eliminating spatial deviations, and improving system accuracy and reliability. High-power lasers (up to hundreds of watts) can burn out sensors if reflected into them, while low-power probe light (milliwatts) may cause feedback oscillations or noise if transmitted into the laser cavity. Wavelength selective separation physically isolates the two optical signals, improving system stability and device lifespan, and complying with laser safety regulations. This beam combiner module 5 configuration also simplifies the optical path structure, increases integration, and eliminates the need for separate optical paths to align with the workpiece. A single focusing module 8 can process both beams simultaneously, making it suitable for compact handheld devices or automated heads, reducing assembly difficulty, minimizing size, and facilitating industrialization. When the system includes a galvanometer, the coaxial beams can be deflected synchronously. If time-of-flight ranging is used and coaxial integration is employed, real-time ranging during scanning can also be achieved. The beam combiner module 5 can be a dichroic flat beam combiner or a dichroic cubic beam combiner, which consists of two right-angle prisms bonded together with a dichroic coating on the inclined surfaces. The laser is incident and transmitted from one end, while the probe light is incident and reflected from the side, resulting in collinear outputs, no beam displacement, and good mechanical stability.

[0058] like Figure 1 As shown, in some modified embodiments of this application, the beam combining module 5 includes an optical substrate, an anti-reflection film, and a reflective film. The optical substrate is inclined. The anti-reflection film is disposed on the side facing the laser emitting module 1, and the anti-reflection film exhibits transmission characteristics for a first wavelength laser beam. The reflective film is disposed on the side facing the distance detection module 6, and the reflective film exhibits reflection characteristics for a second wavelength detection beam.

[0059] The optical substrate refers to a transparent optical material plate that constitutes the main structure of the beam combining module 5. It carries the antireflective and reflective coatings and serves as the propagation medium for both the laser and probe beams. Its physical properties directly affect the system's transmittance, thermal stability, and laser damage threshold. The optical substrate can be BK7 glass, which is low-cost and has good visible-near-infrared transmittance, suitable for low-power, non-harsh environments. It can also be fused silica, which has a low coefficient of thermal expansion and a high laser damage threshold, making it the preferred material for industrial laser cleaning (high-power, pulsed lasers). Furthermore, it can be sapphire, which has extremely high hardness, scratch resistance, and high thermal conductivity, suitable for special protection requirements (such as handheld devices in the field). The tilt angle of the optical substrate can be 45° (incident angle) to achieve 90° beam combining. For example, a fused silica substrate can be used, installed at a 45° tilt.

[0060] An antireflection coating is a multilayer dielectric thin film deposited on the surface of an optical substrate to reduce reflection loss of a specific wavelength of light at the interface. In this application, it is disposed on the side facing the laser emitting module 1 and exhibits high transmission characteristics for a first wavelength (e.g., 1064 nm) of laser light. The antireflection coating can utilize the principle of destructive thin-film interference to cancel out the reflected light from the front and back surfaces, thereby improving transmittance. The antireflection coating can be made of Ta₂O₅ (tantalum pentoxide), which has a high refractive index and stability. Alternatively, it can be made of SiO₂ (silicon dioxide), which has a low refractive index and good matching properties. For example, the antireflection coating can be a single-wavelength antireflection coating optimized for 1064 nm.

[0061] A reflective film is a multilayer dielectric film deposited on the other side of an optical substrate to achieve high reflectivity for beams of a specific wavelength. In this application, it is disposed on the side facing the distance detection module 6 and exhibits high reflectivity for a second wavelength (e.g., 635 nm) probe light. The reflective film can be a high-reflectivity dielectric film with low absorption, high damage threshold, and strong wavelength selectivity. The center wavelength can be 635 nm or 940 nm, and the incident angle can be designed as 45°.

[0062] In some modified embodiments of this application, the antireflective coating has a transmittance of 99.5% or greater for the first wavelength laser beam. A transmittance of 99.5% or greater means that the single-sided reflection / absorption loss is less than or equal to 0.5%, far lower than that of ordinary uncoated glass, allowing higher energy density to reach the workpiece surface, improving cleaning efficiency (especially for stubborn oxide layers and thick paint layers), and avoiding wasted energy. A transmittance of 99.5% or greater also means extremely low absorption (typically <0.2%), which, combined with a fused silica substrate (high thermal conductivity, low expansion), allows for long-term stable operation at high repetition frequencies (e.g., 500 kHz), avoiding focus shift, uneven cleaning, or even equipment downtime caused by heat accumulation, ensuring beam quality stability and equipment reliability during long-term continuous operation. A transmittance of 99.5% or greater means extremely weak backscattered light, resulting in a cleaner electromagnetic and optical environment for the system, enhancing laser output stability, reducing ranging errors, and improving closed-loop control accuracy. For example, modern ion beam sputtering or electron beam evaporation coating technologies can be used to achieve a transmittance of 99.5% or greater. The performance difference between 99.9% and 99.5% is minimal, but the latter has a higher yield and lower cost.

[0063] An optical transmittance (T) of ≥ 99.5% ensures that the high-energy laser beam used for cleaning can pass through the lens perpendicularly without refraction or deflection. The formula is as follows:

[0064]

[0065] in, The laser power passing through the lens, This represents the laser power incident on the lens.

[0066] In some modified embodiments of this application, the reflectivity of the reflective film to the second wavelength probe beam is greater than or equal to 98%. The high reflectivity of the reflective film ensures the intensity of the probe light signal, avoids signal-to-noise ratio degradation, maximizes the retention of probe light energy, and ensures reliable echoes even on low-reflectivity workpieces. It significantly improves the energy utilization rate of the probe light during beam combining, ensuring that the distance detection module 6 can acquire high signal-to-noise ratio echo signals under various workpiece surface conditions, thereby ensuring the stability and repeatability accuracy of the ranging data. Simultaneously, this high reflectivity design effectively suppresses leakage of the probe light into the laser path, avoids crosstalk of optical signals within the system, and provides a reliable sensing basis for achieving high-precision adaptive focusing. Its optical reflectivity R is expressed by the formula:

[0067]

[0068] in, The red light power reflected back to the sensor, This represents the power of the red light emitted by the sensor.

[0069] like Figure 1 As shown, in some modified embodiments of this application, the focal length adjustment module includes a focusing lens 4, a guide rail 3, and a driving mechanism 2. The focusing lens 4 is disposed in the optical path between the laser emitting module 1 and the beam combining module 5. The guide rail 3 extends along the laser emitting direction of the laser emitting module 1, and the focusing lens 4 is slidably connected to the guide rail 3. The driving mechanism 2 is connected to the focusing lens 4 and is used to drive the focusing lens 4 to slide along the guide rail 3 to adjust the effective focal length of the system so that the laser beam is always focused on the surface of the target workpiece.

[0070] The focusing lens 4 is used in conjunction with the focusing module 8 to adjust the axial position of the laser focus relative to the surface of the target workpiece, thereby adjusting the effective focal length of the system. For example, the focusing lens 4 can be a monolithic plano-convex lens, which has a simple structure and low cost. An anti-reflection coating can also be deposited on the focusing lens 4 to improve the laser transmittance.

[0071] Guide rail 3 refers to a precision linear guide mechanism extending along the optical axis, used to constrain the adjustable focusing lens to perform only axial translational movement, preventing tilting or swaying and ensuring optical axis stability. Guide rail 3 can be a cross roller guide rail 3, which offers high rigidity, zero backlash, and nanometer-level stability, suitable for piezoelectric ceramic or voice coil motor drives. Guide rail 3 can also be composed of linear bearings and guide rods, offering low cost and large stroke, suitable for stepper motor and lead screw drive structures. The length of guide rail 3 can be 30mm. Since the length of guide rail 3 is limited, the focal length adjustment range is also limited. When the distance data measured by the red light displacement sensor (distance detection module 6) is transmitted to the control system, and the control system detects that the current distance exceeds the focal length adjustment range, the control system will send a signal to the laser to shut down laser emission.

[0072] The drive mechanism 2 refers to an electromechanical actuator connected to the adjustable focusing lens, used to generate precise axial displacement according to control commands. In some embodiments, the output force of the drive mechanism 2 can be fed back by the displacement response system to achieve closed-loop focusing. The drive mechanism 2 can be the piezoelectric ceramic drive, voice coil motor, stepper motor, etc., as described above. For example, the drive mechanism 2 can use a miniature piezoelectric ceramic motor: resolution up to 0.5 μm, linear speed greater than 10 mm / s, rotational speed greater than 300° / s, stall force of 0.02 N (linear), operating voltage of 2.8 V, power consumption less than 150 mW during movement, capable of linear or rotational motion, and featuring small size, high precision, high speed, and low power consumption.

[0073] like Figure 3 As shown, the focusing lens 4 is mounted on a miniature piezoelectric ceramic motor (drive mechanism 2). The miniature piezoelectric ceramic motor is configured to drive the focusing lens 4 to move along the optical axis to change the axial position of the laser focus relative to the surface of the target workpiece, thereby maintaining the laser beam always focused on the surface of the workpiece. The calculation formula is as follows:

[0074]

[0075] Right now .

[0076] Where f1 is the distance between the focusing lens 4 and the center of the galvanometer, f2 is the distance between the center of the galvanometer and the focusing module 8, and f3 is the distance between the laser focus and the focusing module 8; f1 can be adjusted by the driving mechanism 2, which in turn adjusts f3, thereby adjusting the position of the laser focus so that the laser beam is always focused on the surface of the workpiece.

[0077] In some modified embodiments of this application, a limiting structure is provided on the guide rail 3 to limit the position of the focusing lens 4 so that the focusing lens 4 can move within a set range.

[0078] A limiting structure refers to a physical constraint device or geometric feature installed on a mechanical motion system (such as a guide rail 3, slider, lead screw, etc.) to limit the travel range of moving parts, preventing them from exceeding the travel boundaries, thereby protecting optical elements (such as the focusing lens 4) from collisions or overloads; ensuring that the focusing range meets the optical design requirements, and thus improving the system's repeatability and reliability. The function of the limiting structure is to limit the maximum and minimum positions of the focusing lens 4 along the guide rail 3, ensuring it remains within the effective focusing range and preventing it from exceeding the focus adjustment range and causing damage to other non-working areas. A mechanical stop structure can also be installed on the guide rail 3, with protrusions, steps, pins, or independent stops at both ends or specific positions of the guide rail 3, blocking the focusing lens 4 support (or slider) when it moves to that position. Mechanical stop structures are simple, reliable, and low-cost. For example, the limiting structure can be an integrally formed limiting boss at the end of the guide rail 3, or a screw-fixed limiting post. The limiting structure can use rubber pads, silicone pads, springs or polyurethane buffer blocks as the limiting contact surface to reduce impact noise and mechanical wear, making it suitable for high-precision or quiet environments.

[0079] In some modified embodiments of this application, the focusing module 8 has an anti-focus, so that the probe light reflected from the surface of the target workpiece can be transmitted in reverse along the original optical path and returned to the distance detection module 6 via the beam combining module 5; the distance detection module 6 is a time-of-flight ranging sensor with coaxial transceiver capability, and the probe light emitted by it shares the same optical axis with the receiving field of view, so that part of the echo light reflected by the workpiece can return to the receiving unit of the distance detection module 6 along the original path.

[0080] Antifocality refers to the conjugate focal characteristic, meaning that the focusing optical system has the optical path reversibility of the light reflected from the reflecting surface located at its focal point, allowing the reflected light to pass back through the optical system and return to the vicinity of the light source. The focusing module 8 (which can be composed of a lens group) focuses the red light (probe light) from the distance detection module 6 onto the workpiece surface (i.e., the focal position). When the workpiece surface reflects this light, if the optical system satisfies the conjugate relationship (i.e., the object plane and image plane are conjugate), the reflected light will propagate strictly in the reverse direction along the original incident path. This design relies on a highly symmetrical, low-aberration focusing optical path to ensure efficient coupling of the echo light back to the detector. The time-of-flight (ToF) sensor calculates distance by measuring the round-trip time of the light pulse. The coaxial transceiver structure (transmitting and receiving share the same optical axis) reflects the probe light from the target workpiece surface, which can propagate in the reverse direction along the original optical path, avoiding the parallax problem in triangulation. It is particularly suitable for distance measurement in small areas, high-precision focusing on vertical surfaces, and a compact integrated optical system. By utilizing a three-in-one design integrating the anti-focus module, coaxial transceiver module, and beam combiner module, the ranging, focusing, and processing functions are integrated, significantly outperforming traditional separate focusing schemes. In devices equipped with galvanometers, a kHz-level high-speed time-of-flight ranging sensor can be selected, allowing the galvanometer to oscillate at low speeds, thereby improving the accuracy of the distance detection module. Furthermore, the control module can be configured to trigger the distance detection module to perform ranging when the galvanometer module positions the beam to each target point on the scanning trajectory and pauses briefly, thereby obtaining real-time distance information for the corresponding point and further improving the accuracy of the distance detection module.

[0081] like Figure 1 As shown, in some modified embodiments of this application, a control module 9 is further included. The control module 9 is communicatively connected to the distance detection module 6 and the focus adjustment module, respectively. The control module 9 is configured to receive real-time distance information output by the distance detection module 6, which represents the current distance between the handheld laser cleaning dynamic focusing output device and the target workpiece; determine the corresponding target focusing position based on the real-time distance information, generate a corresponding focus adjustment command; and send the focus adjustment command to the focus adjustment module to drive it to dynamically adjust the optical focusing position so that the effective focus of the system matches the target focusing position, thereby ensuring that the laser beam is always accurately focused on the surface of the target workpiece.

[0082] The control module 9 refers to the central processing unit that is communicatively connected to the distance detection module 6, the focus adjustment module, and the laser emission module 1. It is configured to receive real-time distance information, calculate the corresponding target focusing position based on the real-time distance information, generate focus adjustment commands and / or laser enable signals, and drive the focus adjustment module to dynamically adjust the optical focusing position to ensure that the laser beam is always precisely focused on the surface of the target workpiece. The control module 9 can be an embedded microcontroller, a programmable logic controller, or a field-programmable gate array (FPGA). For example, the control module 9 can use an ARM Cortex-M4 core chip, employing a 32-bit Reduced Instruction Set Computer (RISC) processor core, featuring deterministic computation and a low-latency three-stage pipeline, achieving up to 1.25 DMIPS / MHz. Equipped with a single-cycle multiply-accumulate (MAC) unit and optimized single-instruction multiple-data (SIMD) instructions, it can efficiently execute digital signal processing tasks. A single-precision floating-point unit (FPU) can also be optionally added to enhance floating-point computation capabilities. Supporting the Thumb-2 instruction set, it enables optimal mixing of 16 / 32-bit instructions, effectively reducing code size without compromising performance. Compared to 8-bit devices, the code size is less than three times larger, increasing code density and saving memory space. It can also utilize an integrated nested vector interrupt controller (NVIC), supporting up to 240 interrupts with low latency and low jitter interrupt response characteristics. No assembly programming is required; interrupt service routines can be written directly in pure C, ensuring timely handling of critical events and guaranteeing system real-time performance. CoreSight debugging and tracing capabilities are provided, supporting Joint Test Action Group (JTAG) or 2-pin serial wire debugging (SWD) connections. It also supports multi-processor debugging and real-time tracing, facilitating program debugging and system optimization for developers. Control module 9 possesses high-speed data processing and instruction output capabilities, and includes a built-in multi-scene focal length database (preset optimal cleaning focal length parameters for different materials such as metal, plastic, and ceramic), which users can directly access without manual debugging. Control module 9 can be integrated with a laser emitter, power module, and human-machine interface into a handheld host. The interface uses a 3.5-inch touch screen, which can display working parameters such as current focal length, cleaning power, scanning speed, repetition frequency, scanning interval, pulse width, and scanning length in real time, making it convenient for operators to monitor and adjust.

[0083] The control module 9 detects distance information in real time and dynamically adjusts the optical focusing position accordingly, ensuring that the laser beam is always precisely focused on the surface of the workpiece, regardless of whether it is flat, curved, or has local undulations. This avoids spot enlargement or excessive energy density caused by defocusing, improving contaminant removal efficiency while effectively protecting the integrity of the substrate, making it particularly suitable for high-requirement scenarios such as precision components and cultural relic restoration. Without manual intervention, the system can automatically track changes in workpiece morphology, achieving continuous and efficient cleaning of irregular curved surfaces such as pipes, blades, and molds. This capability significantly expands the application boundaries of laser cleaning equipment, driving its upgrade from a planar processing tool to an intelligent three-dimensional surface processor.

[0084] In some modified embodiments of this application, the control module 9 is communicatively connected to the laser emitting module 1. The control module 9 is configured to compare the real-time distance information output by the distance detection module 6 with a preset safe working distance threshold. When the real-time distance information is greater than the safe working distance threshold, the control module 9 generates a laser disable command and sends it to the laser emitting module 1 to control it to stop outputting the laser beam.

[0085] The safe working distance threshold is a preset maximum allowable working distance (e.g., 100 mm). Exceeding this distance will prevent effective focusing or pose a risk of irradiation. Real-time distance information is the distance between the current device and the target workpiece cleaning surface, output by the distance detection device. The laser disable command can be a digital signal communication message or an analog enable signal to turn off the laser. By comparing the real-time distance with the preset safety threshold, once the distance between the handheld laser cleaning dynamic focusing output device and the workpiece exceeds the safe range, the laser output is immediately cut off, fundamentally avoiding unintended laser irradiation of operators, surrounding equipment, or the environment, and effectively reducing the risk of occupational health and safety accidents.

[0086] After the equipment is started, the red light displacement sensor (distance detection module 6) and the galvanometer synchronously enter the working state. The galvanometer swings according to the preset cleaning trajectory. After each swing cycle (swing angle range ±θ, θ is set according to the cleaning requirements), the 635nm red light emitted by the red light displacement sensor is reflected by the 45° reflecting mirror (beam combining module 5) and then uniformly projected onto the surface of the workpiece to be cleaned. The red light projected onto the workpiece surface undergoes diffuse reflection, and the reflected light returns along the original optical path. After being reflected again by the 45° reflecting mirror, it enters the red light displacement sensor. The red light displacement sensor performs photoelectric conversion and data processing on the reflected light signal, and collects the distance data between the cleaning head and the workpiece surface in real time. Its sampling frequency f is set to f > 100Hz to meet the distance monitoring requirements under dynamic working conditions. The relationship between the sampling period T and the sampling frequency is as follows: The red light displacement sensor transmits the collected distance data to the equipment control system (control module 9) in real time via the data bus, providing position feedback signals for the subsequent dynamic adjustment of the focal length of the focusing lens 4.

[0087] After receiving distance data detected by the red light displacement sensor, the control system (control module) compares it with the preset optimal cleaning focal length. If the detected distance exceeds the optimal focal length, it immediately generates a focal length adjustment command, calculates the optimal focal length for the current distance, and transmits the signal to the miniature piezoelectric ceramic motor to change the focal length. This ensures that the system's effective focal length matches the target focusing position, thereby ensuring that the laser beam is always precisely focused on the surface of the target workpiece. The accuracy range of the focal length command is controlled within... 0.01mm; When the distance data from the red light displacement sensor exceeds the optimal cleaning range, the control system sends a signal to the laser to shut off the laser beam. The control unit calculates the optimal focal length and immediately transmits it to the drive unit. After receiving the command, the drive unit uses a miniature piezoelectric ceramic motor to control the focusing lens to move continuously left and right, with a response time of 0.01mm. Within 5ms, the focusing lens moves along the optical axis, adjusting the position of the focused spot in real time to ensure that the spot is always within the optimal cleaning energy density range on the workpiece surface. After the dynamic focusing actuator adjusts the focus, the first swing of the galvanometer illuminates the surface to be cleaned with red light. The red light displacement sensor also continuously detects and collects distance data in real time, feeding it back to the control unit to form a closed-loop control system of detection-adjustment-feedback. If the shape of the working surface changes again, the distance data is transmitted to the data processing and command generation device again to generate a focus adjustment command, avoiding focusing failure caused by sudden changes in the workpiece surface.

[0088] The following section uses the typical industrial scenario of cleaning rust from welded stainless steel pipes as an example to illustrate in detail the specific implementation process and device parameter settings of the dynamic focusing output method.

[0089] Implementation scenarios and prerequisites:

[0090] The workpiece to be cleaned is a 304 stainless steel pipe (200mm in diameter). There is localized rust in the weld area, with a rust layer thickness of 0.1mm-0.3mm and a maximum height difference of 5mm on the weld surface.

[0091] Initial setup of the device: The operator selects the stainless steel rust cleaning mode from the multi-scene focal length database through the touch screen of the handheld host. The system automatically loads the initial parameters - optimal cleaning focal length 80mm, laser power 120W, and scanning speed 500mm / s.

[0092] Testing and Calibration: After the equipment is started, the red light displacement sensor (distance detection module 6) inside the cleaning head first performs a baseline distance detection on the non-corroded area of ​​the pipeline and measures an initial distance of 85mm. The main control unit (control module 9) automatically calculates the initial focal length adjustment amount (+5mm) and drives the piezoelectric ceramic motor to move the focusing lens 4 to the corresponding position to complete the preheating calibration.

[0093] The dynamic focused cleaning implementation steps include:

[0094] Phase 1: Cleaning of the rusted edge area.

[0095] The operator holds the cleaning head and moves it slowly along the edge of the weld (the moving speed matches the system scanning speed). The laser displacement sensor collects distance data in real time at a frequency of 100Hz. When the distance is detected to drop from 85mm to 82mm (that is, the workpiece surface height increases by 3mm), the data is immediately transmitted to the control system.

[0096] The main control unit compares the preset optimal cleaning focal length (80mm), calculates the distance that the focusing lens needs to be moved closer to the workpiece, and then sends an adjustment command to the piezoelectric ceramic motor.

[0097] The piezoelectric ceramic motor completes the displacement within 5ms, at which time the focused spot accurately falls on the workpiece surface, and the energy density is maintained at 1.5J / cm² (the optimal energy density range for stainless steel rust cleaning), achieving precise peeling of the rust edge without scratching the substrate.

[0098] Phase 2: Cleaning of the weld seam with varying elevations.

[0099] When the cleaning head moves to the highest point of the weld, the sensor detection distance drops to 78mm (7mm lower than the reference distance). The control system responds quickly and generates a lens (focusing lens) movement command, so that the laser is focused on the highest point of the weld.

[0100] Meanwhile, the system uses a closed-loop feedback mechanism to collect distance data again within 0.1 seconds after the lens moves, confirming that the current focusing distance is 80mm and ensuring no adjustment deviation.

[0101] During this process, even if there is a height change of 2mm / s on the workpiece surface (such as due to slight hand tremors of the operator), the dynamic focusing system can still correct it in real time to avoid problems such as "incomplete cleaning" (too low energy density) or "substrate damage" (too high energy density) caused by focal length shift.

[0102] Phase 3: Verification of cleaning effect and re-washing.

[0103] After completing a round of cleaning, operators can view the focus adjustment log (which records the distance changes and adjustments at each location) through the human-machine interface and observe the weld surface.

[0104] If local residual rust is found (mostly in the initial blind spot), the manual cleaning mode can be activated. At this time, the red light displacement sensor continuously detects the distance of the residual area, and the system automatically uses the dynamic focusing logic. The operator only needs to align with the residual point, and the equipment can automatically complete the focus adjustment and precise cleaning. The cleaning efficiency is 50% higher than that of traditional equipment.

[0105] Implementation results and parameter comparison:

[0106] Table 1

[0107]

[0108] As shown in Table 1, the dynamic focusing output method and device of the present invention can realize closed-loop control of "real-time detection - rapid adjustment - precise cleaning" in irregular workpiece cleaning scenarios, which significantly improves cleaning quality and efficiency, while reducing the operating threshold and personnel fatigue.

[0109] The following section uses the typical industrial scenario of cleaning rust from welded stainless steel pipes as an example to illustrate in detail the specific implementation process and device parameter settings of the dynamic focusing output method.

[0110] Implementation scenarios and prerequisites:

[0111] Workpiece to be cleaned: 6061 aluminum alloy sheet is a commonly used industrial structural component. Due to long-term outdoor use, the epoxy resin coating on the surface has developed local cracks (crack width 0.1mm-0.3mm), and there are 0.5mm-1mm coating lift-offs at the edges; slight bending deformation is concentrated in the central area of ​​the sheet (maximum surface height difference 3mm), forming an arc-shaped convexity, not a local depression, to avoid collision between the cleaning head and the workpiece.

[0112] Initial device settings: Select aluminum alloy coating peeling mode on the touch screen, and load preset parameters into the system: optimal cleaning focal length 100mm, laser cleaning power 80W, pulse power 50kHz, scanning spacing 0.1mm (to ensure no coating is missed during peeling), and scanning speed 800mm / s (power should be reduced during coating peeling to avoid substrate oxidation). This embodiment takes laser marking as an example, aiming to achieve high-precision QR code marking on metal surfaces (marking accuracy ±2μm, scanning speed ≥5000mm / s).

[0113] Detection and calibration: The red light displacement sensor (distance detection module) samples the data, and the average value is taken as the reference distance. The initial distance is measured to be 108mm. The system will issue a prompt after calibration is completed.

[0114] The dynamic focused cleaning implementation steps include:

[0115] Large-area coating peeling: The operator moves the cleaning head at a constant speed, and the red light displacement sensor collects distance data at a frequency of 120Hz. When the distance at the bending point of the board is detected to drop to 105mm (the height increases by 3mm), the main control unit (control module) quickly calculates the adjustment amount +3mm.

[0116] Precise focusing execution: The piezoelectric ceramic motor completes the displacement of the focusing lens within 4ms, and the focused spot energy density is stabilized at 0.8J / cm² (the optimal range for aluminum alloy coating peeling), avoiding yellowing and oxidation of the substrate caused by excessive power;

[0117] Edge and corner treatment: For the edge and corner areas of the board (where the distance changes by up to 2mm), the closed-loop feedback system completes the "detection-adjustment-confirmation" within 0.08s to ensure that there is no coating residue at the corner and that the surface roughness of the substrate is ≤Ra0.8μm.

[0118] Implementation results and parameter comparison:

[0119] Table 2

[0120]

[0121] As can be seen from Table 2, the dynamic focusing output method and device of the present invention can realize closed-loop control of real-time detection-rapid adjustment-precise cleaning in irregular workpiece cleaning scenarios, significantly improving cleaning quality and efficiency, while reducing the surface roughness of the substrate surface.

[0122] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A handheld laser cleaning dynamic focusing output device, characterized in that, include: Laser emitting module (1), used to output laser beam; The distance detection module (6) is configured to emit a detection beam toward the target workpiece and obtain real-time distance information between the handheld laser cleaning dynamic focusing output device and the target workpiece based on the reflection signal of the detection beam. A beam combining module (5) is disposed in the intersection area of ​​the outgoing optical paths of the laser emitting module (1) and the distance detection module (6). The beam combining module (5) is configured to have different optical response characteristics to the laser beam and the detection beam, so that the laser beam and the detection beam propagate collinearly along the same principal optical axis after being combined. The focusing module (8) is located in the downstream optical path of the beam combining module (5) and is used to focus the laser beam and the probe beam together on the same working area of ​​the target workpiece. The focal length adjustment module is at least partially disposed in the optical path between the laser emission module (1) and the beam combining module (5). The focal length adjustment module is communicatively connected to the distance detection module (6) and is configured to dynamically adjust the effective focal length of the system according to the real-time distance information detected by the distance detection module (6), so that the laser beam is always focused on the surface of the target workpiece.

2. The handheld laser cleaning dynamic focusing output device according to claim 1, characterized in that, Also includes: The galvanometer module (7) is located between the beam combining module (5) and the focusing module (8). It is used to receive the collinear beam after the laser beam and the probe beam are combined, and to deflect the beam in at least one dimension according to the control command, so as to drive the focused spot of the collinear beam to scan the surface of the target workpiece according to a preset trajectory, thereby realizing regional cleaning operation.

3. The handheld laser cleaning dynamic focusing output device according to claim 1, characterized in that, The beam combining module (5) is configured to exhibit transmission characteristics for a laser beam of the first wavelength and reflection characteristics for a probe beam of the second wavelength, so that the laser beam and the probe beam propagate collinearly along the same principal optical axis.

4. The handheld laser cleaning dynamic focusing output device according to claim 3, characterized in that, The beam combining module (5) includes: Optical substrate, tilted; An antireflective coating is disposed on the side facing the laser emitting module (1), and the antireflective coating exhibits transmission characteristics to a laser beam of the first wavelength; A reflective film is disposed on the side facing the distance detection module (6), and the reflective film exhibits reflective properties to the detection beam of the second wavelength.

5. The handheld laser cleaning dynamic focusing output device according to claim 4, characterized in that, The antireflective coating has a transmittance of 99.5% or greater for a laser beam of the first wavelength. And / or, the reflective film has a reflectivity of 98% or greater for the probe beam of the second wavelength.

6. The handheld laser cleaning dynamic focusing output device according to claim 1, characterized in that, The focal length adjustment module includes: A focusing lens (4) is disposed in the optical path between the laser emitting module (1) and the beam combining module (5); The guide rail (3) extends along the laser emission direction of the laser emission module (1), and the focusing lens (4) is slidably connected to the guide rail (3); The driving mechanism (2) is connected to the focusing lens (4) and is used to drive the focusing lens (4) to slide along the guide rail (3) to adjust the effective focal length of the system so that the laser beam is always focused on the surface of the target workpiece.

7. The handheld laser cleaning dynamic focusing output device according to claim 6, characterized in that, The guide rail (3) is provided with a limiting structure to restrict the position of the focusing lens (4) so ​​that the focusing lens (4) can move within a set range.

8. The handheld laser cleaning dynamic focusing output device according to claim 1, characterized in that, The focusing module (8) has an anti-focus point, which allows the detection light reflected from the surface of the target workpiece to be transmitted in reverse along the original optical path and returned to the distance detection module (6) via the beam combining module (5). The distance detection module (6) is a time-of-flight range sensor with coaxial transmission and reception capability. The detection light emitted by the sensor shares the same optical axis with the receiving field of view, so that part of the detection light reflected by the workpiece can return to the receiving unit of the distance detection module (6) along the original path.

9. The handheld laser cleaning dynamic focusing output device according to claim 1, characterized in that, Also includes: The control module (9) is communicatively connected to the distance detection module (6) and the focus adjustment module, respectively; The control module (9) is configured to receive real-time distance information output by the distance detection module (6); determine the corresponding target focusing position according to the real-time distance information, generate the corresponding focal length adjustment command; and send the focal length adjustment command to the focal length adjustment module to drive it to dynamically adjust the optical focusing position so that the effective focal length of the system matches the target focusing position, thereby ensuring that the laser beam is always accurately focused on the surface of the target workpiece.

10. The handheld laser cleaning dynamic focusing output device according to claim 9, characterized in that, The control module (9) is communicatively connected to the laser emitting module (1). The control module (9) is configured to compare the real-time distance information output by the distance detection module (6) with a preset safe working distance threshold. When the real-time distance information is greater than the safe working distance threshold, the control module (9) generates a laser disable command and sends it to the laser emitting module (1) to control it to stop outputting the laser beam.

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