Method for irradiating a workpiece surface using a multi-beam laser system and a laser system

Abstract

The present invention relates to a method and a device for increasing the output power of a laser in a compact portable device for laser processing (cleaning) workpieces by an ablation method for removing a damaged layer, rust and other foreign substances, and deposits from a solid surface. The method is based on the formation of a junction of an independent laser fiber and a combiner surface in a specific configuration, the combiner being made of the same material as the fiber. Embodiments of the device implement the method and include emitter devices for manual or automatic use. Compactness of the system is achieved, the total output power of the laser and the performance of the system are increased, and a processing mode of the workpiece is selected according to the radiation power density level.

Description

Technical Field

[0001] The present invention relates to a method and a device for increasing the output power of a laser in a compact portable device for laser processing (cleaning) workpieces by ablation for removing a damaged layer, rust, and other foreign substances and deposits from a solid surface. Background Art

[0002] Lasers have a wide range of application fields: from telecommunications to space applications of high-power lasers. However, there is a class of lasers with an average power of 100 - 200 W, which are convenient to use in compact portable devices, such as hand-held welding equipment, cleaners for removing rust, paint, and sedimentary rock on the bottom of marine vehicles, and other cases. In such devices, laser radiation is emitted through an optical fiber or through an optical fiber combiner. The output power in the first case is lower than that in the second case. As a result, the performance of the device is reduced. However, the problem of combining multiple optical fibers from independent laser sources into a total beam is also controversial and can be carried out in different ways.

[0003] In the patent with the publication number RU2439627C2, in order to combine an optical fiber bundle in the form of a multi-core optical fiber, a method and a mounting device with multiple capillaries are used. The tube fibers are inserted into the capillaries for combination and then fused by heating. The material of this device is glass with a refractive index lower than that of quartz fibers and a lower melting temperature. This means that the optical and physical properties of this material have boundaries, the optical losses increase, and the beam quality at the output end of this melting device (or more precisely, at the output end of the hot-melting device) deteriorates because quartz does not melt in this technology. This technology is labor-intensive and has poor renewability.

[0004] An invention in the fields of mechanical engineering, instrument making, laser engineering and technology is proposed in the patent with publication number RU 2619692 C1, and it can be used for laser cleaning of unwanted layers and contaminants, especially for removing rust, scale, paint from the surfaces of various metal objects such as steel pipes, sheets, wheel sets of rolling stock in railway transportation, coins, bronze, weapons, etc. A method for cleaning metals includes using a light spot with a power density of its laser radiation on the surface to be cleaned sufficient to cause a thermal destruction process of the coating. To achieve the occurrence of the thermal destruction process of the coating, continuous laser radiation is used, and the light spot on the surface of the article continuously moves along a closed circular path, and the center of curvature moves linearly along a path of any configuration to simultaneously obtain a continuous processed strip. The following technical result is achieved: by increasing the width of the strip of the processed surface, the performance of laser cleaning of the metal surface is improved, but the power is limited by the power of one laser used, and it is difficult to reach a compromise between the compactness of the proposed solution and the required power of dozens of kilowatts. After all, not every continuous laser with a power of 10 kW can be carried around.

[0005] Therefore, the problem of providing a compact portable laser with an average power of a kilowatt laser requires additional consideration, and this problem has been considered in the present invention. Summary of the Invention

[0006] The object of the present invention is to develop a method for increasing the output power of an average power laser without sacrificing the radiation quality at the output end of the laser, which is specifically achieved by combining the fiber outputs from different lasers for processing the surfaces of solids, machine parts and structures using a compact portable system. The use of this method makes it possible to realize a new laser system and device for cleaning solid surfaces. Its technical results are as follows: the system is compact, the total output power of the laser and the system performance are improved, and the processing mode of the workpiece is selected according to the radiation power density level.

[0007] The essence of the method lies in irradiating the surface of the workpiece with a multi-beam laser system, including emitting laser radiation by combining independent lasers with fiber outputs on the input surface of at least one combiner, the combiner being in the form of a device made of the same matrix material as the fiber of the laser, and fusing these lasers with the input plane of the device at the output ends of these lasers, so that before fusing, the laser fibers are oriented at right angles to the surface of the device plane, have straight cleavages and do not contact each other, and the output opposite surfaces of the device ensure that the laser beams are emitted in free space and diverge from each end of the fiber towards the optical system. In the position configuration of the fusion points of the fiber ends and the device on the input surface, a scalable 3 - 5 times magnified image is formed on the processed surface.

[0008] There is also proposed a laser system for processing the surface of a workpiece by ablation using the radiation of laser sources arranged with respect to one another, for implementing the above method, the system comprising:

[0009] - a laser source coupled by fusion with an input surface in the housing of the emitter module;

[0010] - an optical system in the form of an objective lens;

[0011] - a dynamic optical system that deflects the radiation beam at the output of the optical system in the housing of the emitter module;

[0012] - a protective window located at the radiation outlet of the laser system, and an optical input cable leading to the window and having optical fibers from each laser, the laser system being located in the housing of the emitter module.

[0013] Other advantages of the present invention will be disclosed in the description and illustrated in the drawings and exemplary embodiments.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a photograph of the fusion point of the input surface of a quartz crystal resonator with quartz fibers from lasers arranged in a row.

[0016] Figure 2 is a photograph showing the light spot in the focal plane of the objective lens.

[0017] Figure 3 shows a block diagram of the laser system, with the arrows conditionally indicating the path of the light beam.

[0018] Figure 4 shows the angular orientation of the distribution pattern of the light spots in the focal plane of the objective lens.

[0019] Figure 5 is an arrangement of two devices with optical fibers truncated by a plurality of planes. DETAILED DESCRIPTION

[0020] As described above, one of the aims of the proposed method for irradiating the surface of a workpiece is to increase the output power of the laser system without sacrificing the radiation quality from each laser. To do this, the fusion of the output optical fibers from each laser with the surface of the device is carried out in such a way that, before fusion, the optical fibers are oriented at right angles to the surface, have straight cleavages and do not touch each other (see Figure 1 ), without distorting the output aperture of each optical channel. In Figure 2In the case of the photograph shown, the size of the aperture at the output end of each of the five optical fibers is 20 μm, and after passing through the device after fusion, the aperture and the gap between the optical fibers undergo a proportional increase, typically 3 to 5 times, depending on the power density required in the light spot in the focal plane of the objective lens, which in turn depends on the power at the input end of the device. Obviously, the type, wavelength of the laser used and the optical fiber itself can be different, depending on the problem to be solved by the application of this method.

[0021] Therefore, it is crucial that the positions of the ends of the optical fibers spaced apart from each other on the input surface of the device at the fusion point of the device are configured such that the quality of the output radiation from each laser at the output end of the optical system is not degraded due to the mutual influence of adjacent junctions, and the pulsed and / or continuous radiation from multiple laser sources is transmitted to the irradiation point of the workpiece without distorting the quality of each light beam due to the scalable increase in the distribution pattern of the junctions on the device, and without deforming the distribution of the light spots in the focal plane of the objective lens.

[0022] Figure 3 A block diagram of a system for implementing a method of irradiating a workpiece surface is shown. This method increases the output power of a laser used in a compact portable device by summation. The compact portable device is used for laser processing (cleaning) of a workpiece by ablation of a damaged layer, rust and other foreign substances and deposits from a solid surface. The beam energy from laser sources 1 - 5 is provided through a cable 6 having optical fiber output ends 7 - 11. The ends of the optical fiber output ends 7 - 11 are fused to the input surface 12 of the device 13. The radiation is reflected on a reflecting device (mirror or prism) 14 and is directed to an objective lens 15. The objective lens 15 includes at least one collimating lens 16 and at least one focusing lens 17. At the output end of the objective lens 15, a dynamic optical system 18 that deflects the radiation beam deflects the radiation beam. A protective window 20 protects the objective lens 15 from decomposition products from the surface of the workpiece 19 being processed. The protective window is transparent to the radiation and is located at a position above the surface of the workpiece 21 in the focal plane of the objective lens.

[0023] Importantly, the beam combiner in the form of the device 13 is made of quartz glass or an optical polymer in the laser system.

[0024] Importantly, in the laser system, the objective lens 15 includes at least one collimating lens and at least one focusing lens, and a reflecting device 14 in the form of a mirror or prism at the input end of the objective lens 15, which is used to change the direction of the light beam.

[0025] Importantly, in the laser system, the beam deflection in the dynamic optical system 18 is achieved by a current scanner with a scanning mirror or an optically and mechanically rotatable beam scanning device, where the movement path of the light spot on the processed surface can be translational, rotational, or a combination of translational and rotational.

[0026] It is crucial that in the laser system, the ends at the welding points of the optical fibers with the device are arranged in one direction, with a linearly spaced arrangement between adjacent junctions, and the device itself can be rotated within an angle range of 0 - 90° relative to the X direction of the deflection dynamic system to obtain different fillings of the scanning field (along the X-axis, see Figure 4 ): narrow solid 22, stripe 23, or wide solid 24, depending on the required surface radiation power density and the performance of the ablation process. Meanwhile, in the transverse direction Y, the scanning field is shifted in manual or automatic mode.

[0027] Importantly, in the laser system, the device is made in the form of a cylinder that has a conical part on the side of the optical fiber junction at its truncated top (see Figure 1 ).

[0028] Importantly, in the laser system, an optical combiner (device) in the form of a cylinder with a frustum on the optical fiber side is truncated on the opposite side of its longitudinal axis with two cutting planes to obtain flat devices and the possibility of stacking these devices on top of each other along the plane (see Figure 5 ), thereby increasing the total power at the output end of the system.

[0029] Obviously, another configuration of the optical fiber distribution pattern at the point where the device is welded is also possible. For example, the optical fiber distribution pattern is in the form of a honeycomb or other two-dimensional distribution on one face of the device.

[0030] The present invention is implemented through an example of a 6-channel laser system. By combining the 6 fiber outputs of a pulsed picosecond diode-pumped fiber laser with a central wavelength of 1.06 μm and an average power of 170 W per channel, and in the case of manually implementing the emitter device, it was tested during the process of removing rust from the complex surface of a steel workpiece. That is, when the operator's hand is displaced along the Y-axis in the X-axis scanning direction at a speed of up to 10 cm / s (50 cm 2 / s, with a scanning line width of 5 cm along the X-axis at a scanning frequency of 100 - 300 Hz) ( Figure 4 ). This processing demonstrated the high performance of the above system.

[0031]

[0032]

[0033] Those skilled in the art should be clear that the present invention is not limited to the above embodiments and includes variations within the scope of the claimed rights. Where necessary, the distinguishing features presented in the specification can also be used separately from each other together with other distinguishing features.

Claims

1. A method of irradiating a surface of a workpiece with a multi-beam laser system, comprising outputting laser radiation from a plurality of independent lasers having fiber outputs, by combining these independent lasers on an input surface of at least one optical combiner in the form of a device made of the same substrate as the fibers of the lasers, by fusing the fibers of the lasers to the input surface of the device at the output ends of the fibers, such that before the fusing, the fibers of the lasers are oriented at right angles to the surface of the input surface of the device, have straight cleavage and do not contact each other, and the output surface of the device ensures that laser beams diverging in free space are output from each end of the fiber towards an optical system, forming a scalable 3-5 times magnified image of the ends of the fibers and the gaps between the fibers on the surface of the workpiece, wherein, The end of the optical fiber is fused to the device.

2. A multi-beam laser system for processing a workpiece surface by ablation using the radiation of a laser source having an optical fiber output, for implementing the method according to claim 1, the system comprising: - A transmitter module, the transmitter module including the laser source, the optical fiber output of the laser source being combined on the output surface of at least one optical combiner in the form of a device by fusion with the output surface of the at least one optical combiner; - An optical system in the form of an objective lens; - A dynamic optical system that deflects the radiation beam at the output of the optical system in the transmitter module; - A protective window and an optical input cable, the protective window being located at the radiation exit of the laser system, the laser system being located in the transmitter module.

3. The laser system according to claim 2, wherein, The device is made of quartz glass or an optical polymer.

4. The laser system according to claim 2, wherein, The objective lens includes at least one collimating lens and at least one focusing lens, and a reflecting device in the form of a mirror or prism at its input for changing the direction of the light beam.

5. The laser system according to claim 2, wherein The deflection of the light beam in the dynamic optical system is achieved by a current scanner having a scanning mirror or an optically and mechanically rotatable light beam scanning device, and the movement path of the light spot on the surface of the workpiece is translational or rotational, or a combination of the translation and the rotation.

6. The laser system according to claim 2, wherein, The device is made in the shape of a cylinder, the cylinder having a conical portion on the side of the optical fiber knot at its truncated top, or alternatively including a plurality of planes truncating the cylinder to obtain a flat device for stacking these devices on top of each other, thereby increasing the total power at the output end of the system.

7. The laser system according to claim 2, wherein, The laser system is a laser surface cleaner.

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