Composite laser light path system

Abstract

The invention discloses a composite laser light path system which comprises a laser source, a half-wave plate, a frequency doubling crystal, a beam splitter and a beam combiner which are sequentially arranged along a light path, the laser source is used for emitting a waveform-adjustable fundamental frequency light beam, the half-wave plate is rotatably arranged and used for changing the light polarization direction of the fundamental frequency light beam, the frequency doubling crystal is used for frequency doubling of part of the fundamental frequency light beam, and the beam combiner is used for combining the frequency doubling crystal and the beam splitter. The beam splitter is used for separating the frequency multiplication light beam and the fundamental frequency light beam which is not subjected to frequency multiplication, the separated frequency multiplication light beam is transmitted along a first channel and is incident to the beam combiner, and the separated fundamental frequency light beam is transmitted along a second channel and is incident to the beam combiner; the first channel and the second channel are different in optical path, and the beam combiner is used for combining the light beams of the two channels into a composite light beam. According to the composite laser light path system, the size, the shape and the relative position of the composite light spot can be changed, the light field absorption rate is changed, and the composite laser light path system is suitable for different machining scenes.

Description

Technical Field

[0001] The present application relates to the field of laser processing, and in particular to a composite laser optical path system. Background Art

[0002] In the field of laser processing, the processing of non-ferrous metals (aluminum, copper, etc.) is a research hotspot. The absorption rate of non-ferrous metals to near-infrared light is less than 5%, and a large amount of laser light is reflected, affecting construction safety and the service life of the laser; while the absorption rate of non-ferrous metals to green light is more than 40%, which is significantly higher than that of near-infrared light. At present, higher-power green light is generally obtained by frequency doubling near-infrared light using frequency doubling crystals. However, the power of green light formed by frequency doubling near-infrared light is still limited by the frequency doubling efficiency of the frequency doubling crystals, resulting in the inability to increase the power of the green laser all the time. When non-ferrous metals are heated to melt, they have a good absorption rate for near-infrared light. Therefore, near-infrared light that has not been frequency doubling can also be used to form a composite laser. However, the control of the wavelength components of the composite laser and the spot shape formed by the composite laser has not been studied.

[0003] Therefore, it is necessary to design a new composite laser optical path system to address the above problems. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a composite laser optical path system for comprehensively controlling the wavelength components of the composite light spot by rotating the half-wave plate and adjusting the waveform of the fundamental frequency light beam; and changing the size, shape and relative position of the composite light spot by adjusting the optical path.

[0005] To achieve the above-mentioned purpose and other related purposes, the purpose of the present application is to provide a composite laser optical path system, which includes a laser source, a half-wave plate, a frequency doubling crystal, a beam splitter and a beam combiner arranged in sequence along the optical path, wherein the laser source is used to emit a fundamental frequency beam, and the waveform of the fundamental frequency beam is adjustable; the half-wave plate can be rotatably arranged to change the light polarization direction of the fundamental frequency beam; the frequency doubling crystal is used to double the frequency of part of the fundamental frequency beam, and output the frequency doubling beam and a second fundamental frequency beam that has not been doubled; the beam splitter is used to separate the frequency doubling beam and the second fundamental frequency beam that has not been doubled, the separated frequency doubling beam is transmitted along a first channel and incident on the beam combiner, and the fundamental frequency beam is transmitted along a second channel and incident on the beam combiner, and the optical path of the first channel and the second channel are different; the beam combiner is used to combine the frequency doubling beam transmitted from the first channel and the fundamental frequency beam transmitted from the second channel to form a composite beam.

[0006] Optionally, the optical path of the first channel and / or the second channel is variable, thereby changing the energy distribution of the composite light spot formed by the composite light beam.

[0007] Optionally, a beam displacement element is provided in the first channel and / or the second channel, and the beam displacement element is used to translate the optical axis of the light beam.

[0008] Optionally, it is characterized in that the light beam displacement element can be moved parallel to the optical axis to change the optical path and / or the position of the optical axis of the optical channel.

[0009] Optionally, the beam displacement element can rotate around a fixed rotation axis parallel to itself to drive the oscillation of the light beam.

[0010] Optionally, the beam displacement element includes a first reflector and a second reflector sequentially arranged along the first channel or the second channel.

[0011] Optionally, the reflectivity of the first reflector and the second reflector to the light beam transmitted through the first channel or the second channel is greater than 95%.

[0012] Optionally, the fundamental frequency light beam emitted by the laser source is formed by combining a continuous light beam and a pulse light beam, the power of the continuous light beam can be adjusted, and the power, pulse width and repetition rate of the pulse light beam can be adjusted.

[0013] Optionally, the laser processing system further comprises a first focusing mirror, which is arranged between the half-wave plate and the frequency doubling crystal to converge the fundamental frequency light beam outputted through the half-wave plate.

[0014] Optionally, a wave plate is provided in the first channel and / or the second channel, and the wave plate includes a 1 / 2 wave plate and a 1 / 4 wave plate, which are used to adjust the polarization of the light beam.

[0015] Compared with the prior art, the composite laser optical path system of the present application has at least the following beneficial effects: 1. The optical axes of the doubled frequency light beam and the fundamental frequency light beam in the laser processing optical path of the present application can change with the processing state. According to different processing requirements, the translation and rotation of the first channel and / or the second channel light beam can be controlled to achieve 1. Control the optical path of the two light beams to change the divergence effect of the light beam, and then change the size of the light spot formed by the two light beams; 2. Control the degree of overlap of the optical axes of the two light beams to change the shape and eccentricity of the composite light spot; 3. Control one of the two light beams to rotate around the other light beam, thereby changing the shape and eccentricity of the composite light spot; when one of the light beams rotates periodically around the other light beam, a dot ring effect of one light spot rotating periodically around another light spot can be achieved. The optical elements in the processing optical path are controlled by a software-driven motor, and the size, shape and relative position of the composite light spot are comprehensively adjusted to achieve the purpose of changing the light spot situation according to the processing conditions and better adapt to various processing environments; 2. When the laser is in use, by adjusting the rotation angle of the half-wave plate, the polarization direction of the fundamental frequency light emitted by the laser source is changed to match the polarization direction required by the phase matching direction of the frequency doubling crystal, the frequency doubling efficiency of the frequency doubling crystal can be changed, thereby changing the power ratio of the second fundamental frequency beam that has not been frequency doubling and the frequency doubling beam in the composite light beam, and the wavelength component of the composite light spot can be slowly adjusted; by adjusting the light output waveform of the laser source, the power density of the fundamental frequency beam passing through the frequency doubling crystal can be changed, thereby changing the frequency doubling efficiency of the frequency doubling crystal. The repetition rate of the pulse beam in the composite light beam emitted by the laser source is the frequency of the periodic change of the light output power of the laser source, and the repetition rate of the pulse beam generally reaches the kHz level. Therefore, by adjusting the light output waveform of the laser source, the wavelength component of the composite light spot can be quickly adjusted; by controlling the rotation of the half-wave plate and the light output waveform of the laser source, a combination of fast adjustment and slow adjustment can be achieved, and the wavelength component of the composite light spot can be adjusted in a diversified manner to adapt to different processing environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0017] Figure 1 Schematic diagram of the structure of the composite laser optical path system described in the embodiment.

[0018] Figure 2 Schematic diagram comparing the output pulse and spot energy distribution of the composite laser optical path system described in the embodiment. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element, or there can be one or more centered elements therebetween. When an element is described as "electrically connected" to another element, it can be directly connected to another element, or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0021] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] The present application provides a composite laser optical path system, such as Figure 1 As shown, it includes a laser source 11, a half-wave plate 12, a frequency doubling crystal 14, a beam splitter 17 and a beam combiner 20 which are arranged in sequence along the optical path.

[0023] In the present application, the laser source 11 is used to emit a fundamental frequency beam, and the waveform of the fundamental frequency beam is adjustable. Adjusting the waveform of the fundamental frequency beam emitted by the laser source 11 can not only change the waveform of the composite beam output by the subsequent beam combiner, but also change the power density of the fundamental frequency beam incident on the frequency doubling crystal 14, thereby achieving the purpose of quickly adjusting the wavelength component of the composite beam output by the beam combiner and quickly adjusting the material's absorption rate of the light field. The half-wave plate 12 can be rotatably arranged to dynamically change the polarization direction of the fundamental frequency beam; the half-wave plate 12 is arranged between the laser source 11 and the frequency doubling crystal 14, and can be rotated with the optical axis as the rotation axis. Rotating the half-wave plate 12 can change the polarization direction of the fundamental frequency beam, and is used to change the angle between the polarization direction of the fundamental frequency beam and the polarization direction component in the phase matching direction of the frequency doubling crystal, thereby changing the frequency doubling efficiency. Furthermore, a rotating device can be added at the position of the half-wave plate 12 to control the polarization direction of the slow-adjusted fundamental frequency light beam, thereby changing the frequency doubling efficiency, and then changing the wavelength component of the composite light spot, realizing the slow adjustment of the material's absorption rate of the light field, combining slow adjustment with fast adjustment, and changing the wavelength component of the composite light spot in multiple ways, realizing fast adjustment + slow adjustment of the material's absorption rate of the light field.

[0024] The frequency doubling crystal 14 is used to frequency double a portion of the fundamental frequency light beam, and output a frequency doubled light beam and a second fundamental frequency light beam that has not been frequency doubled; the frequency doubling crystal 14 frequency doubles the component whose light polarization direction of the fundamental frequency light beam coincides with the polarization component in the phase matching direction of the frequency doubling crystal 14, so as to frequency double a portion of the fundamental frequency light beam. It can be understood that when the light polarization direction of the fundamental frequency light beam completely coincides with the phase matching direction of the frequency doubling crystal 14, the frequency doubling efficiency reaches a peak value. After the frequency doubling crystal 14 frequency doubles a portion of the fundamental frequency light beam, it outputs a frequency doubled light beam and a second fundamental frequency light beam that has not been frequency doubled.

[0025] The beam splitter 17 is used to separate the frequency-doubled beam and the second fundamental frequency beam that has not been frequency-doubled. The separated frequency-doubled beam is transmitted along the first channel and incident on the beam combiner, and the fundamental frequency beam is transmitted along the second channel and incident on the beam combiner. The optical paths of the first channel and the second channel are different. The beam splitter 17 is used to separate the two beams of light into a frequency-doubled beam and a second fundamental frequency beam that has not been frequency-doubled and enter different optical channels. The separated frequency-doubled beam enters the first channel for transmission, and the separated second fundamental frequency beam that has not been frequency-doubled enters the second channel for transmission. A beam combiner 20 is set at the end of the two channels to combine the frequency-doubled beam transmitted from the first channel and the fundamental frequency beam transmitted from the second channel to form a composite beam. In the composite beam, the optical axes of the frequency-doubled beam and the fundamental frequency beam coincide, and the optical paths are not equal. One embodiment is to increase the optical path of one of the beams of light in the first channel or the second channel to form a straw hat-shaped spot energy distribution on the processing surface, so as to achieve the processing effect of controlling the molten pool.

[0026] Compared with the existing technology, the composite laser optical path system of the present application has at least the following beneficial effects: 1. The optical path can be changed with the processing state. The size, shape and relative position of the composite light spot can be adjusted by controlling the position and state of the beam displacement element in the first channel and / or the second channel. The control mechanism of the beam displacement element is set to be related to the processing state, so that the light spot can be changed with the processing state. 2. By controlling the rotation of the half-wave plate 12, the angle between the polarization direction of the fundamental frequency light beam and the polarization component in the phase matching direction of the frequency doubling crystal is controlled, thereby controlling the component of the fundamental frequency light beam in the direction of the polarization component in the phase matching direction of the frequency doubling crystal 14, and controlling the power ratio between the doubled frequency light beam output by the frequency doubling crystal 14 and the second fundamental frequency light beam that has not been doubled, thereby realizing slow adjustment of the wavelength component of the composite light spot by slowly or quasi-statically rotating the half-wave plate 12 to adapt to more processing environments.

[0027] The technical solution of the present application is now further described in conjunction with the following embodiments.

[0028] In one embodiment, the optical path of the first channel and / or the second channel is variable, thereby changing the energy distribution of the composite light spot formed by the composite light beam. In the far field, the light spot diverges as the distance increases. Therefore, by controlling the optical path of the first channel and the second channel, the size of the composite light spot can be controlled. After the beam is combined, the spot size of the second fundamental frequency beam that has not been doubled is different from that of the doubled frequency beam; by controlling the length of the first channel, the spot size of the doubled frequency beam when the beam is combined can be controlled, and by controlling the length of the second channel, the spot size of the fundamental frequency beam when the beam is combined can be controlled. Based on the coordinated control of the length of the first channel and the length of the second channel, the energy distribution and spot shape of the composite light beam can be controlled.

[0029] Optionally, the optical path of the first channel remains unchanged, and the optical path of the second channel is changed, so that in the composite light spot formed, the frequency-doubled light spot formed by the frequency-doubled light beam remains unchanged, and the center of the fundamental frequency light spot formed by the fundamental frequency light beam coincides with the center of the frequency-doubled light spot, and the size of the fundamental frequency light spot increases as the optical path of the second channel increases, and decreases as the optical path of the second channel decreases; Optionally, the optical path of the second channel remains unchanged, and the optical path of the first channel is changed, so that in the formed composite light spot, the fundamental frequency light spot remains unchanged, and the center of the double frequency light spot coincides with that of the fundamental frequency light spot, and the size of the double frequency light spot increases as the optical path of the first channel increases, and decreases as the optical path of the first channel decreases; Optionally, the optical path lengths of the first channel and the second channel can be changed simultaneously, the spot centers of the frequency doubled light spot and the fundamental frequency light spot coincide, the size of the frequency doubled light spot changes with the optical path length of the first channel, and the size of the fundamental frequency light spot changes with the optical path length of the second channel.

[0030] It can be understood that when the optical path lengths of the first channel and the second channel are equal, the relative sizes of the frequency-doubled light spot and the fundamental frequency light spot are not necessarily equal.

[0031] In one embodiment, a beam displacement element 180 is provided in the first channel and / or the second channel, and the beam displacement element 180 is used to translate the optical axis of the light beam. Specifically, the beam displacement element 180 can move parallel to the optical axis to change the optical path and / or optical axis position of the optical channel to meet processing requirements in various occasions.

[0032] For example, when the optical axis of the first channel is offset by controlling the movement of the beam displacement element 180, the frequency-doubled light spot output from the optical path is eccentric, and forms a teardrop-shaped composite light spot together with the fundamental frequency light spot; or, when the optical axis of the second channel is offset by controlling the movement of the beam displacement element 180, the fundamental frequency light spot output from the optical path is eccentric, and forms a teardrop-shaped composite light spot together with the frequency-doubled light spot; or, by controlling the movement of the beam displacement element 180, the optical axes of both the first channel and the second channel are offset and the optical axes after the combined beams no longer overlap, and the light spots formed by the two beams output from the optical path are separated or form a teardrop-shaped composite light spot.

[0033] Taking laser welding as an example, when welding turns, the spot shape can be controlled while controlling the laser head to turn. The moving direction of the preheating spot can be changed from the front of the original welding moving direction to the front of the turning direction. The preheating spot is controlled to always be in the moving direction of the laser head, realizing more efficient and faster automatic control of laser welding.

[0034] It is understandable that the purpose of the beam splitter, beam combiner and beam displacement element is to change the optical path of the second fundamental frequency beam that has not been frequency doubled and the frequency doubled beam. The purpose of changing the optical path of the beam is to adjust the divergence of the beam so that different spot sizes can be formed when the beam is combined. For this purpose, optical elements such as triangular prisms can also be set in the first optical path and / or the second optical path and their parallel movement can be controlled to change the optical path and thus change the divergence of the beam. Based on the coordinated control of the first channel length and the second channel length, with the optical element that can change the divergence of the beam, the energy distribution and spot shape of the composite beam can be controlled.

[0035] It can be understood that another purpose of the parallel movement of the beam displacement element is to change the position of the optical axis of the optical channel in which it is located. Based on this purpose, beam displacement elements such as parallel plates and periscope prisms can also be set in the first optical path or the second optical path. Through these beam displacement elements, the position of the optical axis of the optical channel in which it is located can also be changed, so that the fundamental frequency spot and the doubled frequency spot are eccentric to form a teardrop-shaped composite spot.

[0036] Optionally, the beam displacement element can rotate around a fixed rotation axis parallel to its own optical axis to drive the swing of the beam. A composite spot is formed in which the spot of one laser beam is at the center and the spot of the other laser beam swings around the frequency-doubled spot, which is beneficial to control the welding molten pool and suppress welding spatter.

[0037] In one embodiment, the beam displacement element includes a first reflector 18 and a second reflector 19 sequentially arranged along the first channel or the second channel. Figure 1 When the doubled frequency beam is transmitted along the first channel and the second fundamental frequency beam without frequency doubling is transmitted along the second channel, a beam displacement element 180 is arranged in the second channel, including a moving device 181 to move the first reflector 18 and the second reflector 19. It can be understood that the first moving device 1811 and / or the second moving device 1812 in the moving device 181 can be arranged as a parallel moving device, so that the first reflector 18 and the second reflector 19 can move parallel to the optical axis, including but not limited to the following embodiments.

[0038] When the first reflector 18 and the second reflector 19 move in parallel at equal distances and in the same direction relative to the first channel, the beam combining effect of the beam combiner 20 remains unchanged, the optical path of the fundamental frequency light beam changes, and the size of the fundamental frequency light spot changes; or, when the first reflector 18 and the second reflector 19 move in parallel at equal distances relative to the first channel and move away from the first channel at the same time, the optical path of the fundamental frequency light beam becomes larger, and the fundamental frequency light spot becomes larger; or again, when the first reflector 18 and the second reflector 19 move in parallel at equal distances relative to the first channel and move closer to the first channel at the same time, the optical path of the fundamental frequency light beam becomes smaller, and the fundamental frequency light spot becomes smaller.

[0039] In the present scheme, a 180° turn of the propagation direction of the light beam is achieved by two reflectors, the first reflector 18 and the second reflector 19. Therefore, the effect of the first reflector 18 and the second reflector 19 moving away from each other at equal distances is equivalent to the first reflector 18 and the second reflector 19 moving away from each other at equal distances relative to the first channel and at the same time; the effect of the first reflector 18 and the second reflector 19 moving towards each other at equal distances is equivalent to the first reflector 18 and the second reflector 19 moving towards each other at equal distances relative to the first channel and at the same time.

[0040] In other embodiments, the first reflector 18 is fixed, and the second reflector 19 is controlled to move parallel to the optical axis, the fundamental frequency spot and the frequency doubling spot are eccentric to form a teardrop-shaped composite spot, and the parallel movement direction is related to the spot position of the teardrop-shaped composite spot. The movement direction of the second reflector 19 can be controlled to achieve changes in the eccentricity and eccentricity direction of the composite spot; or, the second reflector 19 is fixed, and the first reflector 18 is controlled to move parallel to the optical axis, the fundamental frequency spot and the frequency doubling spot are eccentric to form a teardrop-shaped composite spot, and the parallel movement direction is related to the spot position of the teardrop-shaped composite spot. The movement direction of the first reflector 18 can be controlled to achieve changes in the eccentricity and eccentricity direction of the composite spot; or, the processing system controls the first reflector 18 and the second reflector 19 to move parallel to the optical axis, and the spot shape can be changed in a linked manner to meet more processing requirements.

[0041] In one embodiment, the first moving device 1811 and / or the second moving device 1812 in the moving device 181 may be configured as a combination of a parallel moving device and / or a rotation moving device.

[0042] The first reflector 18 is fixed, and the intersection of the plane formed by the optical axis of the second reflector 19 and the center of the composite light spot after the beam combiner is coincident and passes through the second reflector 19 is set as the fixed rotation axis. The processing system controls the second reflector 19 to swing and rotate with the fixed rotation axis as the rotation axis, and the eccentric direction of the fundamental frequency light spot can be controlled to tilt to other angles. Taking the laser welding of copper as an example, when the fundamental frequency light spot is used as the edge of the straw hat light spot to preheat the molten pool, the position of the preheating light spot in the optical path can be changed in conjunction with the tilt of the second reflector 19 when the laser head tilts and turns, so as to better adapt to the processing requirements. It can be understood that the second reflector 19 is fixed, and the processing system controls the first reflector 18 to translate and / or rotate, or the processing system controls the first reflector 18 and the second reflector 19 to translate and / or rotate at the same time, which can be included in this solution. The linkage control of the first reflector 18 and the second reflector 19 by the processing system can obtain more changes in the size, shape, and relative position of the light spot to adapt to more processing requirements.

[0043] The first reflector 18 is fixed, and the position where the center of the composite light spot after beam combining by the beam combiner coincides and the optical axis passing through the second reflector 19 is set as the fixed rotation axis. The processing system controls the second reflector 19 to rotate with the fixed rotation axis as the rotation axis, which can form a swinging composite light spot. In the field of laser welding, the control of the welding molten pool and the suppression of welding spatter can be performed. It can be understood that the second reflector 19 is fixed, and the position where the center of the composite light spot after beam combining by the beam combiner coincides and the optical axis passing through the first reflector 18 is set as the fixed rotation axis. The processing system controls the first reflector 18 to rotate with the fixed rotation axis as the rotation axis, which can achieve the same effect.

[0044] The first reflector 18 is fixed, and the straight line where the center of the composite light spot after beam combining by the beam combiner coincides and the angular bisector of the angle between the two optical axes passing through the second reflector 19 is set as the fixed rotation axis. The processing system controls the second reflector 19 to rotate with the fixed rotation axis as the rotation axis, while the optical axis passing through the second reflector 19 rotates with the fixed rotation axis as the rotation axis, so that a rotating teardrop-shaped composite light spot can be formed, and the control of the welding molten pool and the suppression of welding spatter can be performed in the field of laser welding. It can be understood that the second reflector 19 is fixed, and the straight line where the center of the composite light spot after beam combining by the beam combiner coincides and the angular bisector of the angle between the two optical axes passing through the second reflector 19 is set as the fixed rotation axis. The processing system controls the second reflector 19 to rotate with the fixed rotation axis as the rotation axis, while the optical axis passing through the second reflector 19 rotates with the fixed rotation axis as the rotation axis, so that the same effect can be achieved.

[0045] It can be understood that since the green laser can maintain the quality of single-mode beam at high power output of kilowatts, it can provide lower divergence and smaller focus during processing, effectively improving the processing accuracy. Therefore, when the light formed by the frequency doubling crystal is in the green band, it is very useful in laser welding applications such as forming Figure 1 The optical path shown in the figure makes the optical path of the first channel where the double frequency beam is located as short as possible, and the double frequency spot is located at the center of the composite spot. This is a better solution, which can make full use of the good beam quality of green light to improve processing accuracy and achieve deep fusion welding. Of course, the solution in which the beam displacement element 180 is set in the first channel, or the solution in which the beam displacement element 180 is set in the first channel and the second channel at the same time, is also naturally included in this solution. Figure 1 The interpretation does not constitute any limitation on this case.

[0046] Preferably, when the first reflector and the second reflector are arranged in the first channel, the reflectivity of the doubled frequency light beam is greater than 95%; when the first reflector and the second reflector are arranged in the second channel, the reflectivity of the fundamental frequency light beam is greater than 95%. For light of different wavelengths transmitted in different channels, the high-reflection film to be plated on the first reflector and the second reflector should have corresponding film layer refractive index and film thickness settings to reduce energy loss in the optical path.

[0047] Optionally, the fundamental frequency beam emitted by the laser source is formed by combining a continuous beam and a pulse beam, the power of the continuous beam can be adjusted, and the power, pulse width and repetition rate of the pulse beam can be adjusted. Figure 2 The output power and beam output power shown are the energy distribution curves of each spot corresponding to t1 to t6, and the energy distribution curve represents the energy distribution of the composite spot. Among them, the red curve represents the energy distribution of the spot without frequency doubling in the composite beam, the green curve represents the energy distribution of the spot of the frequency doubling beam in the composite beam, and the purple coordinate axis represents the process of the optical path difference of the second channel increasing over time. It can be seen that by changing the optical path difference of the second channel, the spot size of the fundamental frequency spot can be changed; by modulating the waveform of the fundamental frequency beam, different energy distributions can be given to the composite spot. The repetition rate of the pulse beam can be adjusted to the kHz level through the software control circuit, and the adjustment frequency of the distribution of the wavelength proportion of the spot can also reach the kHz level accordingly. Combined with the slow adjustment of the wavelength component by the half-wave plate 12, the composite laser optical path system is given the ability to adjust the wavelength component of fast adjustment + slow adjustment.

[0048] Optionally, the laser processing system also includes a first focusing mirror 13, which is arranged between the half-wave plate 12 and the frequency doubling crystal 14 to converge the fundamental frequency light beam output by the half-wave plate. The frequency doubling efficiency of the frequency doubling crystal 14 is related to the power density of the incident fundamental frequency light; only the fundamental frequency light incident from a specific angle and with a specific polarization into the frequency doubling crystal can obtain a better frequency doubling efficiency. Therefore, a focusing mirror 13 is required to converge the fundamental frequency light whose polarization direction is changed by the half-wave plate 12 and then incident into the frequency doubling crystal 14, so that the incident angle of the fundamental frequency light is more consistent, and at the same time, the spot area formed on the surface of the frequency doubling crystal when the fundamental frequency light is incident into the frequency doubling crystal 14 is reduced, and the power density is increased to obtain a better frequency doubling effect.

[0049] Optionally, a wave plate is provided in the first channel and / or the second channel, and the wave plate is used to adjust the polarization of the light beam, wherein the wave plate can be a 1 / 2 wave plate or a 1 / 4 wave plate. After the light beam passes through the frequency doubling crystal 14 and is emitted by the frequency doubling crystal 14, the relative relationship between the polarizations of the frequency doubling light beam and the second fundamental frequency light beam that has not been frequency doubling is determined; in some optical applications, a specific polarization state may have an important impact on subsequent processing steps or the response of the detector. Modulating the polarization state of the composite light beam is conducive to accurately controlling the absorption rate and detection effect of the laser beam at different angles of different materials. Therefore, a 1 / 2 wave plate can be provided on the first channel and / or the second channel, and the electrically controlled 1 / 2 wave plate can be slowly rotated to obtain relatively different polarization state distributions of the frequency doubling light beam and the fundamental frequency light beam; or a 1 / 4 wave plate can be provided on the first channel and / or the second channel, and the 1 / 4 wave plate can convert the linear polarization of the optical path into circular polarization.

[0050] One embodiment is to set a 1 / 2 wave plate on the first channel, at which time the polarization state of the second channel light beam is controlled by the half-wave plate 12, the polarization state of the first channel light beam is controlled by the 1 / 2 wave plate on the first channel, and the half-wave plate 12 cooperates with the 1 / 2 wave plate on the first channel to give the doubled frequency light beam and the fundamental frequency light beam different linear polarization states; one embodiment is to set a 1 / 2 wave plate on the second channel, at which time the polarization state of the first channel light beam is controlled by the half-wave plate 12, the polarization state of the second channel light beam is controlled by the 1 / 2 wave plate on the second channel, and the half-wave plate 12 cooperates with the 1 / 2 wave plate on the second channel to give the doubled frequency light beam and the fundamental frequency light beam different linear polarization states; one embodiment is to set a 1 / 2 wave plate on both the first channel and the second channel, at which time the polarization state of the first channel light beam is controlled by the 1 / 2 wave plate on the first channel, the polarization state of the second channel light beam is controlled by the 1 / 2 wave plate on the second channel, and the 1 / 2 wave plate on the first channel cooperates with the 1 / 2 wave plate on the second channel to give the doubled frequency light beam and the fundamental frequency light beam different linear polarization states.

[0051] One embodiment is to set a 1 / 4 wave plate on the first channel, at which time the polarization state of the second channel light beam is controlled by the half-wave plate 12, the first channel light beam becomes circularly polarized, and the half-wave plate 12 cooperates with the 1 / 4 wave plate on the first channel to give the doubled frequency light beam and the fundamental frequency light beam different polarization states; one embodiment is to set a 1 / 4 wave plate on the second channel, at which time the polarization state of the first channel light beam is controlled by the half-wave plate 12, the second channel light beam becomes circularly polarized, and the half-wave plate 12 cooperates with the 1 / 4 wave plate on the second channel to give the doubled frequency light beam and the fundamental frequency light beam different polarization states; one embodiment is to set a 1 / 4 wave plate on both the first channel and the second channel, at which time the first channel light beam and the second channel light beam both become circularly polarized, and the 1 / 4 wave plate on the first channel cooperates with the 1 / 4 wave plate on the second channel so that the doubled frequency light beam and the fundamental frequency light beam are changed from linearly polarized light to circularly polarized light.

[0052] The first channel and / or the second channel is provided with a wave plate, which cooperates with the half-wave plate 12 to give the frequency-doubled light beam and the fundamental frequency light beam different polarization states, obtain different light field absorption rates, and thus adapt to more usage scenarios.

[0053] Compared with the prior art, this application has at least the following advantages: 1. The optical axes of the doubled frequency light beam and the fundamental frequency light beam in the laser processing optical path of the present application can change with the processing state. According to different processing requirements, the translation and rotation of the first channel and / or the second channel light beam can be controlled to achieve 1. Control the optical path of the two light beams to change the divergence effect of the light beam, and then change the size of the light spot formed by the two light beams; 2. Control the degree of overlap of the optical axes of the two light beams to change the shape and eccentricity of the composite light spot; 3. Control one of the two light beams to rotate around the other light beam, thereby changing the shape and eccentricity of the composite light spot; when one of the light beams rotates periodically around the other light beam, a dot ring effect of one light spot rotating periodically around another light spot can be achieved. The optical elements in the processing optical path are controlled by a software-driven motor, and the size, shape and relative position of the composite light spot are comprehensively adjusted to achieve the purpose of changing the light spot situation according to the processing conditions and better adapt to various processing environments; 2. When the laser is in use, by adjusting the rotation angle of the half-wave plate, the polarization direction of the fundamental frequency light emitted by the laser source is changed to match the polarization direction required by the phase matching direction of the frequency doubling crystal, the frequency doubling efficiency of the frequency doubling crystal can be changed, thereby changing the power ratio of the second fundamental frequency beam that has not been frequency doubling and the frequency doubling beam in the composite light beam, and the wavelength component of the composite light spot can be slowly adjusted; by adjusting the light output waveform of the laser source, the power density of the fundamental frequency beam passing through the frequency doubling crystal can be changed, thereby changing the frequency doubling efficiency of the frequency doubling crystal. The repetition rate of the pulse beam in the composite light beam emitted by the laser source is the frequency of the periodic change of the light output power of the laser source, and the repetition rate of the pulse beam generally reaches the kHz level. Therefore, by adjusting the light output waveform of the laser source, the wavelength component of the composite light spot can be quickly adjusted; by controlling the rotation of the half-wave plate and the light output waveform of the laser source, a combination of fast adjustment and slow adjustment can be achieved, and the wavelength component of the composite light spot can be adjusted in a diversified manner to adapt to different processing environments; thereby adapting to different processing scenarios, which is beneficial to the improvement of welding speed, the adjustment of molten pool depth and the suppression of welding spatter. Specific processing scenarios include but are not limited to: in optical communication systems, it can achieve long-distance, high-speed data transmission; in laser radar systems, it can be used for applications such as distance measurement, target detection, and three-dimensional imaging; in material processing fields such as laser cutting, laser welding, and laser marking, it can achieve high-precision and high-efficiency laser processing; in industrial measurement and scientific research, it can be used for measuring equipment such as laser interferometers, laser rangefinders, and laser spectrometers. Therefore, this application effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0054] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A composite laser optical path system, characterized in that: The composite laser optical path system comprises a laser source, a half-wave plate, a frequency doubling crystal, a beam splitter and a beam combiner which are sequentially arranged along the optical path, wherein: The laser source is used to emit a fundamental frequency light beam, and the waveform of the fundamental frequency light beam is adjustable; The half-wave plate can be rotatably arranged to change the polarization direction of the fundamental frequency light beam; The frequency doubling crystal is used to frequency-double a portion of the fundamental frequency light beam, and output a frequency-doubled light beam and a second fundamental frequency light beam that has not been frequency-doubled; The beam splitter is used to separate the frequency-doubled light beam and the second fundamental frequency light beam which has not been frequency-doubled, the separated frequency-doubled light beam is transmitted along a first channel and incident on the beam combiner, and the fundamental frequency light beam is transmitted along a second channel and incident on the beam combiner, and the optical paths of the first channel and the second channel are different; The beam combiner is used to combine the frequency-doubled light beam transmitted from the first channel and the fundamental frequency light beam transmitted from the second channel to form a composite light beam.

2. The composite laser optical path system according to claim 1, characterized in that: The optical path of the first channel and / or the second channel is variable, thereby changing the energy distribution of the composite light spot formed by the composite light beam.

3. The composite laser optical path system according to claim 2, characterized in that: A beam displacement element is disposed in the first channel and / or the second channel, and the beam displacement element is used to translate the optical axis of the light beam.

4. The composite laser optical path system according to claim 3, characterized in that: The beam displacement element can move parallel to the optical axis to change the position of the optical axis of the optical channel.

5. The composite laser optical path system according to claim 3, characterized in that: The beam displacement element can rotate around a fixed rotation axis to drive the swing of the light beam.

6. The composite laser optical path system according to claim 3, characterized in that: The beam displacement element includes a first reflector and a second reflector sequentially arranged along the first channel or the second channel.

7. The composite laser optical path system according to claim 6, characterized in that: When the first reflector and the second reflector are arranged in the first channel, the reflectivity of the doubled frequency light beam is greater than 95%; when the first reflector and the second reflector are arranged in the second channel, the reflectivity of the fundamental frequency light beam is greater than 95%.

8. The composite laser optical path system according to claim 1, characterized in that: The fundamental frequency light beam emitted by the laser source is formed by combining a continuous light beam and a pulse light beam. The power of the continuous light beam can be adjusted, and the power, pulse width and repetition rate of the pulse light beam can be adjusted.

9. The composite laser optical path system according to claim 1, characterized in that: The laser processing system also includes a first focusing mirror, which is arranged between the half-wave plate and the frequency doubling crystal to converge the fundamental frequency light beam output by the half-wave plate.

10. The composite laser optical path system according to claim 1, characterized in that: Wave plates are arranged in the first channel and / or the second channel. The wave plates include 1 / 2 wave plates and 1 / 4 wave plates, which are used to adjust the polarization of the light beam.

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