Laser wavelength conversion device

Abstract

The present application relates to the field of laser technology and discloses a laser wavelength conversion device. The device comprises: a polarizing lens; a half-wave plate, arranged on the incident light path of the polarizing lens and connected to an electronic control system, the electronic control system being used to control the half-wave plate to move horizontally into or out of the light path, or to control the angle of the half-wave plate; a frequency doubling light path, connected to the transmission light path or reflection light path of the polarizing lens; a fundamental frequency light serving as the incident light beam; when the electronic control system controls the half-wave plate not to move horizontally into the light path, the fundamental frequency light is incident on the polarizing lens in a vertically polarized state and reflected into the first frequency doubling light path, outputting frequency doubling light of the corresponding wavelength; when the electronic control system controls the half-wave plate to move horizontally into the light path, the polarization state of the fundamental frequency light changes, and the fundamental frequency light is incident on the polarizing lens in a horizontally polarized state and transmitted into the next-stage light path; if subsequent half-wave plates and polarizing lenses are provided in the next-stage light path, the electronic control system further controls the subsequent half-wave plates to move horizontally into the light path or adjust their angles, outputting frequency doubling light of the corresponding wavelength.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser wavelength conversion device. Background Art

[0002] In the field of laser processing, different materials have significantly different absorption rates for wavelengths, so lasers need to be able to output multiple central wavelengths to meet diverse processing needs. The current mainstream solutions have the following drawbacks:

[0003] 1. Solution based on linear motor push-pull mirrors: The optical path is changed by mechanical displacement to select the frequency doubling path. However, the coordinate error of the motor in long-term use will cause the optical path to shift, resulting in reduced frequency conversion efficiency, unstable light spot and power.

[0004] 2. Using an optical switch to select the optical path after beam splitting: The fundamental frequency light intensity needs to be split into multiple optical paths, resulting in an extremely high demand for the average power of the fundamental frequency light. The power requirement increases proportionally with the number of wavelength conversion types, making it difficult to expand the output to more wavelengths.

[0005] The core problem of the above solution is that the cumulative error of mechanical displacement leads to unstable beam pointing, and the power demand and scalability are limited when outputting multiple wavelengths.

[0006] Therefore, there is an urgent need for a device to solve at least one of the above problems. Summary of the Invention

[0007] This application provides a laser wavelength conversion device, which aims to solve the problems of existing laser wavelength conversion solutions, such as the cumulative error of mechanical displacement leading to unstable beam directivity, and limited power requirements and scalability when multi-wavelength output.

[0008] In a first aspect, an embodiment of the present application provides a laser wavelength conversion method, comprising:

[0009] Polarizing lens, used for polarizing and splitting the incident light beam, when the incident light beam is horizontally polarized, it passes through the polarizing lens, and when the incident light beam is vertically polarized, it is reflected on the light-facing surface of the polarizing lens;

[0010] At least one half-wave plate is disposed on the incident light path of the polarizing lens, the half-wave plate being connected to an electronic control system, the electronic control system being used to control the half-wave plate to move laterally into or out of the light path, or to control the angle of the half-wave plate;

[0011] At least two frequency-doubling optical paths, each corresponding to a different wavelength conversion requirement, the frequency-doubling optical path being connected to the transmission optical path or the reflection optical path of the polarizing lens;

[0012] In which, the fundamental frequency light is used as the incident light beam. When the electronic control system controls the half-wave plate not to move horizontally into the optical path, the fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and is reflected into the first frequency doubling optical path, and outputs frequency doubling light of the corresponding wavelength; when the electronic control system controls the half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light changes, and the fundamental frequency light is incident on the polarizing lens in a horizontal linear polarization state and is transmitted into the next-level optical path. If subsequent half-wave plates and polarizing lenses are provided in the next-level optical path, the electronic control system further controls the subsequent half-wave plates to move horizontally into the optical path or adjust the angle, so that the fundamental frequency light is incident on the subsequent polarizing lens in a corresponding polarization state, and is reflected or transmitted into the second frequency doubling optical path and the third frequency doubling optical path, and outputs frequency doubling light of the corresponding wavelength.

[0013] In some embodiments, when a servo motor and a synchronous belt combination are used to control the angle of the half-wave plate, the polarization angle of the fundamental frequency light is adjusted between 0° and 90°, so that the intensity of the light incident on the polarized lens is transmitted and reflected proportionally to achieve simultaneous output of multiple wavelengths, and the intensity ratio of each wavelength can be freely edited by the electronic control system.

[0014] In some embodiments, the laser wavelength conversion device changes the polarization state of the fundamental frequency light by adjusting the position or angle of the half-wave plate through the electronic control system, and enters the corresponding frequency doubling optical path after being split by the polarizing lens, thereby realizing rapid switching or simultaneous output of different wavelengths.

[0015] In some embodiments, the corresponding convertible wavelength is increased by adding a corresponding frequency doubling optical path and a half-wave plate polarization adjustment structure.

[0016] In some embodiments, the fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and reflected into the first frequency doubling optical path, outputting frequency doubling light of a corresponding wavelength, including: when the half-wave plate is not shifted laterally into the optical path, the initial polarization state of the fundamental frequency light is vertical linear polarization, and is reflected after being incident on the light-facing surface of the polarizing lens, and the reflected light path is connected to the input end of the first frequency doubling optical path, a frequency doubling crystal is provided in the first frequency doubling optical path, and the fundamental frequency light is converted by the frequency doubling crystal to output doubled frequency light of a corresponding wavelength.

[0017] In some embodiments, when the electronic control system controls the half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light changes, including: the half-wave plate is driven by a linear motor to move horizontally into the incident optical path, and after the fundamental frequency light passes through the half-wave plate, its polarization state is converted from vertical linear polarization to horizontal linear polarization, and the horizontal linear polarization is directly transmitted through when incident on the polarizing lens, and the transmitted light path is connected to the input end of the next-level optical path, and the next-level optical path includes a subsequent frequency doubling optical path or a polarization splitting structure.

[0018] In some embodiments, if a subsequent half-wave plate and a polarizing lens are provided in the next-stage optical path, the electronic control system further controls the subsequent half-wave plate to move horizontally into the optical path or adjust the angle so that the fundamental frequency light is incident on the subsequent polarizing lens in the corresponding polarization state, and is reflected or transmitted into the second frequency-doubling optical path and the third frequency-doubling optical path, and outputs frequency-doubling light of the corresponding wavelength, including: the subsequent half-wave plate is connected to the electronic control system, and when the fundamental frequency light is transmitted through the preceding polarizing lens in the horizontal linear polarization state, if the electronic control system controls the subsequent half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light is changed to vertical linear polarization again, and when it is incident on the subsequent polarizing lens, it is reflected and enters the second frequency-doubling optical path, and is converted by the frequency-doubling crystal in the second frequency-doubling optical path to output tripled frequency light; if the subsequent half-wave plate is not moved horizontally into the optical path, the fundamental frequency light is transmitted through the subsequent polarizing lens in the horizontal linear polarization state and is directly output.

[0019] In some embodiments, the driving mechanism of the half-wave plate includes a combination of a servo motor and a synchronous belt. The servo motor is linked to the half-wave plate through the synchronous belt, so that the half-wave plate can freely adjust the polarization adjustment angle within the range of 0° to 90°. After the fundamental frequency light is adjusted by the half-wave plate, it is incident on the polarizing lens in a linear polarization state at any angle, so that the ratio of the transmitted light intensity to the reflected light intensity can be precisely controlled by the electronic control system, thereby realizing the simultaneous output of at least two light beams of different wavelengths in a preset ratio.

[0020] In some embodiments, the number of the frequency-doubling optical paths can be expanded by cascading, and each level of the frequency-doubling optical path includes an independent half-wave plate, a polarization lens, and a frequency-doubling crystal. The electronic control system controls the lateral shift state or angle of each level of the half-wave plate step by step, so that the fundamental frequency light undergoes multiple levels of polarization splitting in sequence and then selectively enters the corresponding frequency-doubling optical path, thereby achieving scalable output of multiple wavelengths of doubled frequency light, tripled frequency light, and quadrupled frequency light, and no additional optical switches or complex mechanical structures are required during the expansion process.

[0021] In some embodiments, the electronic control system is integrated with a polarization state and wavelength mapping control module, which pre-stores the correspondence between different half-wave plate positions / angles and output wavelengths. When a wavelength switching or multi-wavelength output instruction is received, the electronic control system automatically calculates and controls the lateral movement path or rotation angle of the half-wave plate, so that the fundamental frequency light accurately enters the target frequency-doubling optical path through polarization splitting, avoiding the cumulative error of traditional mechanical adjustment, and realizing high-precision control of wavelength conversion and millisecond-level fast switching.

[0022] The core of the laser wavelength conversion device provided in the embodiment of the present application is to utilize the polarization characteristics of linearly polarized light to achieve wavelength conversion through the cooperation of a polarization lens and an electrically controlled half-wave plate: the polarization lens transmits horizontally polarized light and reflects vertically polarized light, forming a basis for splitting; the electrically controlled half-wave plate changes the polarization state of the fundamental frequency light through lateral shift or angle adjustment, and controls its entry into different frequency-doubled optical paths (such as doubled and tripled frequency optical paths); there is no need for traditional mechanical push-pull mirrors or high-power beam splitting, and optical path switching is achieved through precise control of the polarization state, avoiding mechanical errors, while supporting multi-stage optical path cascade to expand more wavelengths.

[0023] Compared with the prior art, the invention is creative in that:

[0024] 1. Polarization state control without mechanical displacement: By adjusting the polarization state through a half-wave plate rather than directly mechanically displacing the optical path, the influence of mechanical cumulative error on beam directivity is eliminated in principle, significantly improving stability.

[0025] 2. Multi-wavelength expansion without high power dependency: By cascading polarization splitting structures and frequency-doubling optical paths, adding new wavelengths requires only the addition of corresponding half-wave plates and frequency-doubling modules, without increasing the fundamental frequency optical power. This resolves the conflict between wavelength variety and power requirements in traditional solutions.

[0026] 3. Fast switching and simultaneous multi-wavelength output: The electronic control system uses real-time control of the half-wave plate state to switch wavelengths in milliseconds. By adjusting the polarization angle (such as the servo motor control in Solution 2), multiple wavelengths can be output simultaneously in proportion, breaking through the functional limitations of traditional optical switching solutions.

[0027] The beneficial effects of the provided device include at least:

[0028] 1. Improved pointing stability: Based on the principle of polarization splitting, it avoids mechanical displacement errors, and the beam pointing accuracy is improved by more than 70% compared with traditional solutions. Frequent calibration is not required for long-term use.

[0029] 2. Power adaptability and scalability: The fundamental frequency optical power requirement does not increase significantly with the increase in wavelength types. Adding quadrupled and quintupled optical paths only requires modular expansion, which reduces technical difficulty.

[0030] 3. Multi-function output: supports single wavelength fast switching (switching time < 1ms) and multi-wavelength simultaneous output (light intensity ratio adjustable), meeting the needs of multi-wavelength collaborative operation in complex processing scenarios;

[0031] 4. Extended life: The high-frequency loss of mechanical moving parts is reduced, and the solid-state adjustment structure of the half-wave plate and polarizing lens increases the device life to more than three times that of traditional mechanical solutions.

[0032] In summary, the present invention solves the core problems of unstable directivity and limited multi-wavelength output in the prior art through the innovative combination of polarization state control and optical path splitting, and has significant technological progress and engineering application value.

[0033] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 This is a schematic structural diagram of a laser wavelength conversion device provided in one embodiment of the present application;

[0036] Figure 2 This is a schematic structural diagram of another laser wavelength conversion device provided in one embodiment of the present application;

[0037] Figure 3 This is a structural diagram of a servo motor and a synchronous belt provided in one embodiment of the present application.

[0038] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined, or partially merged, so the actual execution order may vary depending on the actual situation.

[0041] It should be understood that, in order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish between identical or similar items having substantially the same functions and effects. Those skilled in the art will understand that terms such as "first" and "second" do not limit the quantity or order of execution, and that terms such as "first" and "second" do not necessarily define differences.

[0042] It should be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0043] It will also be understood that the term "and / or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0044] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0045] In the field of laser processing, different materials have significantly different absorption rates for wavelengths, so lasers need to be able to output multiple central wavelengths to meet diverse processing needs. The current mainstream solutions have the following drawbacks:

[0046] 1. Solution based on linear motor push-pull mirrors: The optical path is changed by mechanical displacement to select the frequency doubling path. However, the coordinate error of the motor in long-term use will cause the optical path to shift, resulting in reduced frequency conversion efficiency, unstable light spot and power.

[0047] 2. Using an optical switch to select the optical path after beam splitting: The fundamental frequency light intensity needs to be split into multiple optical paths, resulting in an extremely high demand for the average power of the fundamental frequency light. The power requirement increases proportionally with the number of wavelength conversion types, making it difficult to expand the output to more wavelengths.

[0048] The core problem of the above solution is that the cumulative error of mechanical displacement leads to unstable beam pointing, and the power demand and scalability are limited when outputting multiple wavelengths.

[0049] Therefore, there is an urgent need for a device to solve at least one of the above problems.

[0050] To resolve the above, please refer to Figures 1 to 2, an embodiment of the present application provides a laser wavelength conversion device, comprising: a polarizing lens for polarizing and splitting an incident light beam, wherein the incident light beam passes through the polarizing lens when it is horizontally polarized, and is reflected on the light-facing surface of the polarizing lens when it is vertically polarized; at least one half-wave plate is arranged on the incident light path of the polarizing lens, the half-wave plate is connected to an electronic control system, and the electronic control system is used to control the half-wave plate to move horizontally into or out of the light path, or to control the angle of the half-wave plate; at least two frequency-doubling light paths, each corresponding to different wavelength conversion requirements, the frequency-doubling light path being connected to the transmission light path or the reflection light path of the polarizing lens; wherein the fundamental frequency light is used as the incident light beam, when the When the electric control system controls the half-wave plate not to move horizontally into the optical path, the fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and is reflected into the first frequency doubling optical path, and outputs frequency doubling light of the corresponding wavelength; when the electric control system controls the half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light changes, and is incident on the polarizing lens in a horizontal linear polarization state and is transmitted into the next-level optical path. If subsequent half-wave plates and polarizing lenses are provided in the next-level optical path, the electric control system further controls the subsequent half-wave plates to move horizontally into the optical path or adjust the angle, so that the fundamental frequency light is incident on the subsequent polarizing lens in a corresponding polarization state, and is reflected or transmitted into the second frequency doubling optical path and the third frequency doubling optical path, and outputs frequency doubling light of the corresponding wavelength.

[0051] Specifically, this device is based on the polarization characteristics of linearly polarized light, and realizes the selection of wavelength conversion path through the combination of polarizing lens and half-wave plate. The core technical points are as follows: Polarizing lens: polarizes the incident light beam, and the specific characteristics are: when the incident light is horizontally polarized (0°), it passes directly through the lens; when the incident light is vertically polarized (90°), it is reflected on the light-facing surface of the lens; when the incident light is linearly polarized at other angles (such as 45°, 30°), the transmission and reflection are proportionally split (such as 50% transmission and 50% reflection at 45°, 36.7% reflection and 63.3% transmission at 30°). The half-wave plate is set on the incident light path of the polarizing lens and is connected to the electronic control system. It changes the polarization state of the incident light in the following ways: the polarization state is changed when moving horizontally into the light path (such as from vertical linear polarization to horizontal linear polarization), and the initial state is maintained when moving out; Angle fine-tuning (corresponding to Figure 2 Structure): A servo motor drives a synchronous belt to achieve fine adjustment of the polarization angle within a range of 0° to 90°, controlling the ratio of transmitted and reflected light intensities. The frequency-doubling optical path includes at least two independent optical paths (such as doubled, tripled, and quadrupled optical paths), each connected to the transmission or reflection path of the polarizing lens, and the polarization state selection triggers different wavelength conversions.

[0052] The device provided can avoid the mechanical displacement accumulation error of the linear motor pushing and pulling the reflector in the traditional solution. By changing the polarization state through the electrically controlled half-wave plate, the optical path can be switched without mechanical displacement, thereby improving the pointing stability. There is no need to split the fundamental frequency light in advance. The light intensity is dynamically distributed to different optical paths through polarization splitting. The fundamental frequency light power demand does not increase proportionally with the increase in wavelength types, and Figure 2 The provided structure also supports simultaneous multi-wavelength output.

[0053] Figure 1 Provided is a basic solution corresponding to the embodiment of the present application, which is used to achieve switching between double frequency and triple frequency, and the corresponding optical path structure is as follows: Initial state: The fundamental frequency light is vertically polarized, and is reflected when incident on the first polarizing lens, enters the first frequency doubling optical path (double frequency), and outputs double frequency light. The half-wave plate moves horizontally into the optical path: The electronic control system controls the horizontal movement of the first half-wave plate, and the polarization state of the fundamental frequency light is converted to horizontal linear polarization, and enters the next optical path through the first polarizing lens. Next-level optical path (tripling frequency selection): If the second half-wave plate is not moved into the optical path, the fundamental frequency light remains horizontally polarized and is directly output (fundamental frequency light) through the second polarizing lens; if the second half-wave plate is moved into the optical path, the polarization state of the fundamental frequency light is converted to vertical linear polarization, and is reflected at the second polarizing lens, enters the second frequency doubling optical path (tripling frequency), and outputs triple frequency light.

[0054] Figure 2 The expansion scheme provided is corresponding to the embodiment of the present application, which is used to realize the expansion of the multi-frequency optical path: multi-level optical path superposition: Figure 1 On top of this, an additional polarizing lens and half-wave plate combination is added to create a third frequency-doubled optical path (e.g., quadrupled optical path). For example, after the fundamental frequency light is switched by the first two polarizing lenses and half-wave plates, if a third half-wave plate is moved into the optical path, the polarization state is further adjusted, causing the light to be reflected or transmitted by the third polarizing lens and enter the newly added quadrupled optical path, achieving more wavelength output. Each additional wavelength conversion optical path only requires an additional set of half-wave plates and polarizing lenses, following the same principle and without additional technical barriers.

[0055] like Figure 3 As shown, the linear motor can also be replaced with a servo motor and synchronous belt to control the angle of the half-wave plate (continuously adjustable from 0° to 90°) rather than simply shifting it laterally. When the half-wave plate angle is 0°, the incident light is vertically polarized and completely reflected into one of the frequency-doubled optical paths. At 90°, the incident light is horizontally polarized and completely transmitted into the other optical path. At intermediate angles (such as 45°), the light intensity is proportionally distributed between the transmitted and reflected optical paths, achieving simultaneous multi-wavelength output with an adjustable intensity ratio (for example, a 50:50 ratio of doubled and tripled frequency light intensity, or any other ratio).

[0056] The device abandons the traditional solution that relies on mechanical displacement (such as linear motor pushing and pulling the reflector) to switch the optical path. It changes the polarization state by electrically controlling the half-wave plate to avoid the optical path deviation caused by mechanical cumulative error, ensuring the frequency conversion efficiency, spot shape and power stability in long-term use, and extending the service life of the device. No optical switch is required. The half-wave plate state is adjusted in real time by the electronic control system, which can quickly switch to a single wavelength or output multiple wavelengths simultaneously ( Figure 2 The corresponding structure supports proportional light intensity adjustment to meet diverse processing needs. When adding a wavelength conversion optical path, simply superimpose a polarizing lens and half-wave plate combination. The principle is unified, without additional power or technical bottlenecks (unlike traditional beam splitting solutions, where power requirements increase proportionally with wavelength type). Instead of pre-splitting the fundamental frequency light into multiple optical paths, the intensity is dynamically allocated through polarization splitting. The average power requirement for the fundamental frequency light is low and does not increase significantly with the addition of wavelength conversion types, making it particularly suitable for scenarios requiring high power efficiency. Figure 2 The corresponding structure uses a servo motor to fine-tune the angle of the half-wave plate to achieve continuous adjustment of the polarization state from 0° to 90°, and supports free editing of the light intensity ratio (such as allocating it to the doubled and tripled frequency optical paths as needed), meeting the demand for precise control of the intensity ratio of different wavelengths in precision machining.

[0057] This device breaks through the mechanical errors and scalability limitations of traditional wavelength conversion solutions through the innovative combination of polarization splitting and electrically controlled half-wave plates. While maintaining high stability, it achieves rapid multi-wavelength switching, simultaneous output, and flexible expansion, significantly improving the applicability and efficiency of lasers in material processing.

[0058] In some embodiments, as Figure 3 As shown, when a servo motor and a synchronous belt are used in combination to control the angle of the half-wave plate, the fundamental frequency light adjusts the polarization angle between 0° and 90°, so that the intensity of the light incident on the polarizing lens is transmitted and reflected proportionally to achieve simultaneous output of multiple wavelengths, and the intensity ratio of each wavelength can be freely edited by the electronic control system.

[0059] The drive mechanism configuration includes a servo motor and synchronous belt combination integrated on the half-wave plate's mounting bracket. The output shaft of the servo motor is linked to the rotating shaft of the half-wave plate through a synchronous belt, ensuring that the half-wave plate can be adjusted in an angle within the range of 0° to 90° (with an accuracy of up to 0.1°).

[0060] The principle of polarization state adjustment is that the fundamental frequency light is initially vertically linearly polarized (90°). When the servo motor drives the half-wave plate to rotate to an angle of θ, according to Malus's law, the polarization angle of the outgoing light changes to the initial angle ±2θ (the polarization plane of linearly polarized light rotates 2θ when the half-wave plate rotates by θ). For example, when the half-wave plate is rotated by 22.5°, the outgoing light becomes 45° linearly polarized. At this time, when it enters the polarizing lens, the transmitted light intensity and the reflected light intensity each account for 50%. When rotated by 15°, the outgoing light becomes 30° linearly polarized, with the reflected light intensity accounting for approximately 36.7% and the transmitted light intensity accounting for 63.3%.

[0061] Simultaneous multi-wavelength output is achieved by connecting the transmitted and reflected optical paths through the polarizing lens to the doubled and tripled optical paths, respectively. When the half-wave plate is adjusted to an intermediate angle (e.g., 45°), the fundamental frequency light is proportionally split, with the transmitted light entering the doubled optical path (generated by the doubled crystal) and the reflected light entering the tripled optical path (generating tripled light). The intensity ratio of the two paths is precisely controlled by the angle of the half-wave plate.

[0062] The control logic of the electronic control system includes a built-in proportional adjustment algorithm. The user enters the light intensity ratio of the target wavelength (such as double frequency: triple frequency = 3:7) through the human-machine interface. The system automatically calculates the angle to which the half-wave plate should be rotated (such as θ = 19.3°, so that the reflected light intensity accounts for 70%) and sends a control signal to the servo motor to complete the adjustment.

[0063] The embodiment breaks through the "either-or" single wavelength switching mode of traditional solutions and supports continuous angle adjustment from 0° to 90°, achieving a stepless change in the ratio of transmitted / reflected light intensity from 0:100 to 100:0, meeting the stringent requirements for multi-wavelength light intensity ratio in precision processing (such as the simultaneous output of doubled and tripled frequency light of different intensities when processing composite materials). Without the need for additional beam splitters or optical switches, the fundamental frequency light can be proportionally distributed to multiple frequency-doubled optical paths simply by adjusting the angle of the half-wave plate, avoiding the attenuation of the fundamental frequency light power caused by beam splitting in traditional beam splitting solutions and improving energy utilization efficiency. The high-precision closed-loop control of the servo motor ensures that the angle adjustment time is in the millisecond level. Combined with the real-time calculation of the electronic control system, the multi-wavelength output ratio can be quickly switched to adapt to the dynamic needs of material changes during the processing process.

[0064] In some embodiments, the laser wavelength conversion device changes the polarization state of the fundamental frequency light by adjusting the position or angle of the half-wave plate through the electronic control system, and enters the corresponding frequency doubling optical path after being split by the polarizing lens, thereby realizing rapid switching or simultaneous output of different wavelengths.

[0065] Classification of half-wave plate control methods: lateral control (applicable to Figure 1Corresponding structure: The half-wave plate is driven by a linear motor and moves horizontally in a direction perpendicular to the optical path (such as the X-axis). Before moving horizontally into the optical path, the fundamental frequency light maintains the initial vertical linear polarization; after moving horizontally into the optical path, the fundamental frequency light is converted into horizontal linear polarization (polarization state rotated 90°) by the half-wave plate. Angle control (applicable to Figure 2 Corresponding structure): The half-wave plate is driven by a servo motor + synchronous belt and rotates within the range of 0°~90° to change the polarization state angle of the fundamental frequency light (as described in Example 1).

[0066] The optical path switching logic includes: Single wavelength fast switching: When switching from double frequency to triple frequency, the electronic control system controls the front half-wave plate to move horizontally into the optical path (polarization state changes to horizontal). The fundamental frequency light passes through the first polarizing lens and enters the next stage. If the next half-wave plate is synchronously moved horizontally (polarization state changes back to vertical), it is reflected into the triple frequency optical path. The entire switching process does not require mechanical displacement and adjustment of the reflector; only the half-wave plate state needs to be controlled. Simultaneous multi-wavelength output: By controlling the angle of the half-wave plate to an intermediate angle (such as 45°), the fundamental frequency light is split into the transmission and reflection optical paths, triggering the double frequency and triple frequency optical paths to operate simultaneously, outputting two wavelengths.

[0067] This embodiment differs from the traditional solution that relies on the mechanical displacement of the linear motor to push and pull the reflector. This embodiment achieves optical path switching by electrically controlling the position or angle change of the half-wave plate. Mechanical components (such as linear motors) only need to complete simple lateral movement or rotation, without complex trajectory movement, avoiding coordinate offset errors in long-term use and improving the life of the device. It also supports two modes: "lateral movement to switch a single wavelength" and "angle adjustment and simultaneous output of multiple wavelengths". Users can select a mode according to processing requirements (such as using a single wavelength for precision cutting and using a mixed output of multiple wavelengths for surface treatment), with strong adaptability. The lateral movement or angle adjustment action time of the half-wave plate is much shorter than that of the traditional reflector push-pull mechanism (the latter needs to overcome mechanical inertia and has a response time of about hundreds of milliseconds, while the former only takes tens of milliseconds), meeting the real-time wavelength switching requirements in high-speed processing scenarios.

[0068] In some embodiments, the corresponding convertible wavelength is increased by adding a corresponding frequency doubling optical path and a half-wave plate polarization adjustment structure.

[0069] Cascade expansion structure: Building on the existing optical path, the "half-wave plate + polarizing lens + frequency-doubling optical path" structure is stacked in stages. For example: In the first stage, the initial fundamental frequency light (vertically polarized) is reflected by the first polarizing lens into the frequency-doubled optical path (outputting λ / 2). In the second stage, a second half-wave plate (driven by a linear motor for transverse movement) and a second polarizing lens are added. When the first half-wave plate is transversely moved into the optical path (converting the fundamental frequency light to horizontal polarization), after passing through the first polarizing lens, if the second half-wave plate is not transversely moved, the fundamental frequency light remains horizontally polarized and is directly output through the second polarizing lens (fundamental frequency light λ). If the second half-wave plate is transversely moved, the fundamental frequency light is converted to vertical polarization and reflected by the second polarizing lens into the frequency-tripling optical path (outputting λ / 3). In the third stage, a third half-wave plate, a third polarizing lens, and the frequency-quadrupling optical path are added. If the second half-wave plate is not transversely moved (converting the fundamental frequency light to horizontal polarization), the third half-wave plate is transversely moved (converting the fundamental frequency light to vertical polarization), and the third polarizing lens is reflected by the third polarizing lens into the frequency-quadrupling optical path (outputting λ / 4). Each level of half-wave plates is independently connected to the electronic control system. The system controls the lateral shift state of each half-wave plate in hierarchical order through logic circuits or software algorithms (for example, "first-level lateral shift + second-level non-lateral shift + third-level lateral shift" corresponds to the output of quadrupled frequency light).

[0070] Each time a convertible wavelength is added, it is only necessary to copy the standard unit of "half-wave plate + polarization lens + frequency doubling crystal". There is no need to redesign the optical path layout or add complex control logic, and the expansion cost is low. For example, to expand from 3 wavelengths to 5 wavelengths, only two levels of units need to be added, and the technical solution has strong consistency. In the traditional beam splitting solution, each additional optical path needs to split off a part of the fundamental frequency light, resulting in the power of each optical path decreasing as the number of wavelengths increases. However, this embodiment dynamically distributes the light intensity through polarization splitting, and the total power demand of the fundamental frequency light remains unchanged. The power of each optical path can be independently controlled by adjusting the angle of the half-wave plate, which solves the power bottleneck of the traditional solution. The cascade unit adopts a standardized design, and the position of each component is fixed. During maintenance, a certain level of module can be replaced separately without affecting the operation of other optical paths, thereby improving the reliability of the device.

[0071] In some embodiments, the fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and reflected into the first frequency doubling optical path, outputting frequency doubling light of a corresponding wavelength, including: when the half-wave plate is not shifted laterally into the optical path, the initial polarization state of the fundamental frequency light is vertical linear polarization, and is reflected after being incident on the light-facing surface of the polarizing lens, and the reflected light path is connected to the input end of the first frequency doubling optical path, a frequency doubling crystal is provided in the first frequency doubling optical path, and the fundamental frequency light is converted by the frequency doubling crystal to output doubled frequency light of a corresponding wavelength.

[0072] The initial optical path consists of vertically polarized light output by the fundamental frequency light source (the initial polarization state is ensured by the light source's built-in polarizer or crystal), without passing through any half-wave plates (i.e., no half-wave plates are shifted laterally into the optical path). When incident on the first polarizing lens, due to the vertically polarized nature of the light, it is reflected from the lens's facing surface. The reflected light path is precisely aligned with the input end of the first harmonic generation optical path (optical path calibration ensures no offset).

[0073] The frequency-doubling conversion process involves placing a frequency-doubling crystal (such as KTP or BBO, depending on the target wavelength) within the first-harmonic frequency-doubling optical path. Fundamental frequency light (wavelength λ) is incident on the crystal, where it undergoes second harmonic generation (SHG) through nonlinear optical effects, generating doubled-frequency light (wavelength λ / 2). The frequency-doubling optical path also includes optical components such as collimators and focusing lenses to ensure beam quality meets output requirements.

[0074] This embodiment ensures stable entry of the fundamental frequency light into the first harmonic wave optical path by fixing the initial polarization state (vertically polarized light) and the reflective properties of the polarizing lens. This avoids optical path misalignment caused by mechanical displacement in traditional solutions, ensuring consistent output power and beam pointing of the second harmonic wave light over the long term. Without the half-wave plate, the optical path structure is simple, relying solely on the inherent spectroscopic properties of the polarizing lens. This eliminates the need for complex electronic control operations to achieve fundamental wavelength output, making it suitable as the device's default operating mode or backup mode.

[0075] In some embodiments, when the electronic control system controls the half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light changes, including: the half-wave plate is driven by a linear motor to move horizontally into the incident optical path, and after the fundamental frequency light passes through the half-wave plate, its polarization state is converted from vertical linear polarization to horizontal linear polarization, and the horizontal linear polarization is directly transmitted through when incident on the polarizing lens, and the transmitted light path is connected to the input end of the next-level optical path, and the next-level optical path includes a subsequent frequency doubling optical path or a polarization splitting structure.

[0076] The half-wave plate lateral drive includes the half-wave plate being mounted on a guide rail that can slide perpendicular to the optical path and is driven by a linear motor (such as a stepper motor with a ball screw). The motor is connected to the electronic control system and receives "move in" or "move out" instructions.

[0077] The polarization state conversion process involves the linear motor driving the half-wave plate to the center of the optical path when the electronic control system issues a "move horizontally into the optical path" command. After the fundamental frequency light (initially vertically polarized) passes through the half-wave plate, its polarization state rotates 90°, becoming horizontally polarized (due to the half-wave plate's rotational effect on vertically polarized light). When horizontally polarized light strikes the polarizing lens, it passes directly through it, connecting the transmitted light path to the input port of the next optical path. This next optical path may consist of: another "half-wave plate + polarizing lens" beam splitter configuration (for further wavelength selection, such as frequency tripling) or a direct output port (for fundamental frequency output, if further frequency doubling is not required).

[0078] By changing the polarization state through the horizontal movement of the half-wave plate, the mechanical push-pull action of the reflector in the traditional solution is replaced, thus avoiding mechanical wear and coordinate drift caused by long-term displacement of the reflector, and improving the reliability of the device. For example, in the traditional solution, a linear motor may have an error of 0.1mm after pushing and pulling the reflector ten thousand times, while in this embodiment, the horizontal movement of the half-wave plate only needs to be in place, and there is no cumulative error. The next-level optical path after transmission can be flexibly configured. It can be connected to a new frequency-doubling optical path to achieve multi-level wavelength conversion, or it can directly output the fundamental frequency light to meet the needs of flexible switching of "fundamental frequency light / frequency-doubling light", such as using fundamental frequency light for material surface pretreatment and frequency-doubling light for fine processing.

[0079] In some embodiments, if a subsequent half-wave plate and a polarizing lens are provided in the next-stage optical path, the electronic control system further controls the subsequent half-wave plate to move horizontally into the optical path or adjust the angle so that the fundamental frequency light is incident on the subsequent polarizing lens in the corresponding polarization state, and is reflected or transmitted into the second frequency-doubling optical path and the third frequency-doubling optical path, and outputs frequency-doubling light of the corresponding wavelength, including: the subsequent half-wave plate is connected to the electronic control system, and when the fundamental frequency light is transmitted through the preceding polarizing lens in the horizontal linear polarization state, if the electronic control system controls the subsequent half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light is changed to vertical linear polarization again, and when it is incident on the subsequent polarizing lens, it is reflected and enters the second frequency-doubling optical path, and is converted by the frequency-doubling crystal in the second frequency-doubling optical path to output tripled frequency light; if the subsequent half-wave plate is not moved horizontally into the optical path, the fundamental frequency light is transmitted through the subsequent polarizing lens in the horizontal linear polarization state and is directly output.

[0080] The two-stage cascade optical path structure includes the first stage: fundamental frequency light (vertically polarized) passes through the first half-wave plate (unshifted) and is incident on the first polarizing lens, where it is reflected into the doubled frequency optical path (outputting λ / 2). If the first half-wave plate is shifted laterally (converting the fundamental frequency light to horizontal polarization), it passes through the first polarizing lens and enters the second stage optical path. The second stage optical path includes the second half-wave plate (driven by a linear motor) and the second polarizing lens. If the second half-wave plate is unshifted, the fundamental frequency light remains horizontally polarized and is directly output through the second polarizing lens (fundamental frequency light λ). If the second half-wave plate is shifted laterally, the fundamental frequency light is converted to vertical polarization and reflected by the second polarizing lens into the tripled frequency optical path (a frequency-doubling crystal within the optical path achieves third harmonic generation, outputting λ / 3). The hierarchical control of the electronic control system includes the electronic control system executing the control logic in the order of "first level → second level". For example: to output doubled frequency light, the first half-wave plate is not shifted, and the second half-wave plate is in any state (because the first level has been reflected, the second level does not intervene); to output tripled frequency light, the first half-wave plate is shifted (horizontally polarized light passes through the first level), and the second half-wave plate is shifted (vertically polarized light is reflected and enters the tripled frequency).

[0081] Through the combined control of two half-wave plates, the system achieves free switching between three output states: doubled frequency, tripled frequency, and fundamental frequency. This provides greater functionality than traditional single-frequency-doubled solutions (which can only output one doubled frequency). For example, processing copper (requiring λ / 2) and aluminum (requiring λ / 3) requires no equipment replacement; switching can be straightforward. Each doubled frequency optical path is activated only in the corresponding half-wave plate state, preventing crosstalk between the different optical paths (e.g., when the doubled frequency path is operating, the tripled frequency path is deprived of incident light), ensuring output wavelength purity.

[0082] In some embodiments, the driving mechanism of the half-wave plate includes a combination of a servo motor and a synchronous belt. The servo motor is linked to the half-wave plate through the synchronous belt, so that the half-wave plate can freely adjust the polarization adjustment angle within the range of 0° to 90°. After the fundamental frequency light is adjusted by the half-wave plate, it is incident on the polarizing lens in a linear polarization state at any angle, so that the ratio of the transmitted light intensity to the reflected light intensity can be precisely controlled by the electronic control system, thereby realizing the simultaneous output of at least two light beams of different wavelengths in a preset ratio.

[0083] Servo motor drive details include a high-precision rotary servo motor (e.g., a stepper motor with a resolution of 1.8° / step, coupled with a reducer, enabling 0.01° adjustment). This rotational motion is transmitted to the half-wave plate's axis via a synchronous belt. The pulley tooth ratio ensures that the half-wave plate's rotation angle precisely corresponds to the motor control signal. The half-wave plate is mounted on high-precision bearings to ensure zero axial deflection during rotation, maintaining optical path alignment.

[0084] The polarization state adjustment at any angle includes that when the double frequency and triple frequency light intensity need to be output at a ratio of 7:3, the electronic control system calculates that the half-wave plate should be rotated by θ angle so that the reflected light intensity accounts for 30% (according to Malus's law, cos 2 (2θ)=70%, solving for 2θ≈33.2°, θ≈16.6°). The fundamental frequency light is adjusted to θ=16.6° linear polarization by a half-wave plate. When it enters the polarizing lens, 30% of the light intensity is reflected into the triple frequency optical path, and 70% is transmitted into the double frequency optical path. The two double frequency crystals operate separately, outputting two wavelengths simultaneously.

[0085] Unlike traditional solutions, which offer only a binary choice of "total reflection" or "total transmission," this embodiment supports continuous angle adjustment from 0° to 90°, enabling infinitely variable light intensity ratios (theoretically achieving 0.1% accuracy). This meets the precise control of multi-wavelength energy distribution required for scientific research experiments or high-end processing (for example, laser cladding requires a specific ratio of multiple wavelengths to control the melt pool temperature). When the half-wave plate is adjusted to 0° (total reflection) or 90° (total transmission), it degenerates to a single-wavelength output mode. At intermediate angles, multiple wavelengths are activated simultaneously, enabling multiple uses with one device and reducing equipment procurement costs.

[0086] In some embodiments, the number of the frequency-doubling optical paths can be expanded by cascading, and each level of the frequency-doubling optical path includes an independent half-wave plate, a polarization lens, and a frequency-doubling crystal. The electronic control system controls the lateral shift state or angle of each level of the half-wave plate step by step, so that the fundamental frequency light undergoes multiple levels of polarization splitting in sequence and then selectively enters the corresponding frequency-doubling optical path, thereby achieving scalable output of multiple wavelengths of doubled frequency light, tripled frequency light, and quadrupled frequency light, and no additional optical switches or complex mechanical structures are required during the expansion process.

[0087] An example of multi-stage optical path expansion (taking frequency quadrupling as an example) includes: first stage: fundamental frequency light (vertically polarized light) → reflection from the first polarizing lens → frequency doubler light path (λ / 2); second stage: first half-wave plate shifted horizontally (horizontally polarized light) → transmission from the first polarizing lens → second half-wave plate not shifted horizontally (horizontally polarized light) → transmission from the second polarizing lens → direct output of fundamental frequency light (λ); or second half-wave plate shifted horizontally (vertically polarized light) → reflection from the second polarizing lens → frequency tripler light path (λ / 3); third stage: second half-wave plate not shifted horizontally (horizontally polarized light) → third half-wave plate shifted horizontally (vertically polarized light) → reflection from the third polarizing lens → frequency quadrupling light path (λ / 4).

[0088] The cascade control of the electronic control system includes independent control of the lateral movement state of each half-wave plate by the electronic control system through digital IO or bus protocol, forming a "tree-like" optical path selection logic. For example, the output of quadruple frequency light must meet the requirements of "the first half-wave plate is moved horizontally + the second half-wave plate is not moved horizontally + the third half-wave plate is moved horizontally".

[0089] This embodiment is based on a standardized module consisting of "adding a half-wave plate, polarizing lens, and frequency-doubling optical path at each stage." Theoretically, this module can be expanded to n-fold frequency-doubling outputs (limited by the transmittance range of the frequency-doubling crystal material). This expansion requires no adjustments to the existing optical path; simply adding a new module and connecting it to the electronic control system solves the wavelength limitation issue inherent in traditional solutions (for example, traditional beam-splitting solutions support a maximum of three wavelengths, while this embodiment easily expands to more than five). Each module level contains only the necessary optical components and drive mechanism, with no redundant parts. This ensures a manageable size after expansion, making it suitable for integration into compact laser systems.

[0090] In some embodiments, the electronic control system is integrated with a polarization state and wavelength mapping control module, which pre-stores the correspondence between different half-wave plate positions / angles and output wavelengths. When a wavelength switching or multi-wavelength output instruction is received, the electronic control system automatically calculates and controls the lateral movement path or rotation angle of the half-wave plate, so that the fundamental frequency light accurately enters the target frequency-doubling optical path through polarization splitting, avoiding the cumulative error of traditional mechanical adjustment, and realizing high-precision control of wavelength conversion and millisecond-level fast switching.

[0091] The electronic control system hardware architecture includes an integrated polarization state-wavelength mapping control module (which can be implemented by a PLC, single-chip microcomputer, or industrial computer). The built-in storage unit pre-stores the following correspondence: half-wave plate lateral displacement state (moved in / out) → corresponding output wavelength (for example, "first half-wave plate not moved in" → doubled frequency light);

[0092] Half-wave plate rotation angle (0°~90°) → transmitted / reflected light intensity ratio → corresponding multi-wavelength output combination (e.g. θ=45° → double frequency + triple frequency, ratio 1:1).

[0093] The control process includes: when the user inputs the "output tripled frequency light" command through the operation interface, the mapping module retrieves the pre-stored relationship, determines that "the first half-wave plate needs to be moved in + the second half-wave plate needs to be moved in", and sends a control signal to the linear motor; if the input is "output doubled frequency (60%) + tripled frequency (40%) at the same time", the module calculates that the half-wave plate needs to be rotated θ = 25.8° (cos 2 The module uses a power sensor in the optical path to periodically provide feedback, automatically correcting deviations between the actual and theoretical half-wave plate position (e.g., mechanical deformation caused by temperature fluctuations), ensuring long-term control accuracy.

[0094] By pre-storing the mapping relationship, manual adjustment errors are avoided, and the control signal directly corresponds to the target wavelength, eliminating the need for operators to master complex polarization optical principles, thus lowering the threshold for use. For example, novice users only need to select the "stainless steel processing" mode, and the system will automatically configure the half-wave plate state to the optimal wavelength combination. The mapping module's table lookup mechanism eliminates real-time calculation time, and the control signal response time is less than 10ms. Combined with the rapid action of the servo motor, wavelength conversion can be achieved "instantaneously", which is significantly better than the time-consuming process of manually calibrating the optical path in traditional solutions (traditional solutions take several to tens of seconds to switch once). Closed-loop feedback compensates for slight offsets of mechanical components (such as changes in the tightness of the synchronous belt), ensuring the stability of wavelength output during long-term use and avoiding the degradation of processing quality caused by error accumulation in traditional mechanical adjustment solutions.

[0095] In some embodiments, a high-precision optical power sensor (response speed ≤ 1μs, accuracy ±0.1%) is added to the output of the frequency-doubled optical path to collect real-time data on the output light intensity of the doubled and tripled frequencies. The electronic control system integrates an edge computing module with a built-in adaptive learning algorithm based on a BP neural network, enabling real-time data processing and model updating. A high-precision angle encoder (resolution 0.001°) is installed in the half-wave plate drive mechanism to provide real-time feedback on the actual rotation angle of the half-wave plate, forming a closed-loop control system.

[0096] Algorithm Operation Process: Initial training phase: A preset half-wave plate angle range (0°–90°) is used, and corresponding transmitted / reflected light intensity data is collected in 1° increments. A training set of over 2,000 samples (angle-to-intensity ratio mapping) is constructed. The input data is normalized and passed into a three-layer BP neural network (input layer: 1 node: angle; hidden layer: 10 nodes; output layer: 2 nodes: transmitted / reflected light intensity ratio). The model is trained using gradient descent, with an error convergence of ≤0.5%.

[0097] During the real-time control phase, the user sets a target light intensity ratio (e.g., doubled frequency: tripled frequency = 4:6). The edge computing module invokes a trained neural network to reverse-calculate the theoretical half-wave plate angle θ0. A servo motor rotates the half-wave plate to θ0, and an optical power sensor provides real-time feedback on the two output light intensities. If the actual ratio deviates from the target (e.g., ±2%), adaptive adjustment is triggered. An incremental PID algorithm is used to calculate the angle compensation Δθ (Δθ = Kp*e(t) + Ki∫e(t)dt + Kd*de(t) / dt, where e(t) is the real-time error). Δθ is updated every 50ms until the intensity ratio error converges to ≤1%. If the target is not met after three consecutive adjustments, the system automatically switches to online learning mode, adding the current error data to the training set and dynamically updating the neural network model to account for drift issues such as frequency doubling crystal efficiency degradation and lens coating aging over time.

[0098] Abnormal operating condition handling includes when the optical power sensor detects a sudden drop in the output power of a certain frequency-doubling optical path (such as a fluctuation of more than 20%), the system triggers fault diagnosis: first, check whether the half-wave plate angle feedback value is consistent with the theoretical value (to determine whether the drive mechanism is out of step); if the angle is normal, call historical data for comparison to determine whether the frequency-doubling crystal is damaged or the lens is contaminated, and prompt maintenance through the human-machine interface.

[0099] This system overcomes the theoretical errors of traditional open-loop control (such as Malus's law ignoring crystal absorption losses and lens reflectivity deviations). Through real-time feedback and algorithmic compensation, it improves the accuracy of light intensity matching from the traditional ±5% to ±1%, meeting the requirements of applications such as precision lithography and biomedical testing, which require extremely high light intensity stability. Through an online learning mechanism, it automatically adapts to the degradation of optical component performance during long-term operation (such as the temperature-dependent nonlinear coefficient of the frequency-doubling crystal and the aging of the polarization efficiency of the half-wave plate film), eliminating the need for manual regular calibration and reducing maintenance costs by over 70%. By comparing sensor data with historical models, it can proactively identify optical component degradation trends (for example, predicting a frequency-doubling crystal's remaining life of 200 hours), avoiding material scrap caused by sudden failures during processing and improving production continuity.

[0100] In some embodiments, each half-wave plate drive mechanism (linear motor / servo motor) is equipped with a motion trajectory sensor in the cascaded frequency-doubling optical path to collect parameters such as traverse velocity, acceleration, and start / stop times in real time. The electronic control system integrates a multi-objective optimization processor, supporting NSGA-II (non-dominated sorting genetic algorithm) and dynamic programming algorithms to address the coordinated control of multiple half-wave plates.

[0101] The objective function definitions include minimizing switching time (T): maximizing the action time of all half-wave plates (avoiding serial waiting of multi-stage mechanisms); minimizing mechanical loss (L): calculating the loss integral based on the number of motor starts and stops and the rate of acceleration change (extending equipment life); and maintaining optical path collimation (C): constraining the half-wave plate angle adjustment range to avoid exceeding 90°, which would cause polarization state reversal errors.

[0102] State space modeling: The state (transverse shift state / angle value) of each half-wave plate is defined as a discrete variable (e.g., for the nth stage half-wave plate: 0 = no transverse shift, 1 = transverse shift; angle θ n ∈[0°,90°]), construct a state vector S=[s1,s2,…,sm] containing m-level light paths, and the target wavelength combination corresponds to a unique legal state vector S_target.

[0103] The switching path planning process involves, upon receiving a wavelength switching command (e.g., switching from doubled and tripled wavelengths to fundamental frequency and quadrupled wavelengths), the system first calculates the difference between the current state vector S_current and S_target to determine the set of half-wave plates (Ω) to be activated. The linear motors (transverse) and servo motors (angle) in Ω are grouped according to their motion characteristics: linear motors have a shortest transverse path from "current position to target position" (a straight line between two points, with a constant speed of 0.1 m / s); servo motors use an S-shaped acceleration and deceleration algorithm for angle adjustment to avoid start-stop shock (acceleration time ≤ 20 ms). The NSGA-II algorithm is then used to generate a Pareto-optimal solution set, balancing switching time T and mechanical loss L. For example, a parallel control scheme that simultaneously activates multiple half-wave plates is preferred (shortening T but increasing the number of motor starts and stops), while a sequential control scheme is preferred (extending T but reducing motor load). After dynamic planning verifies that the final path is free of mechanical conflicts (e.g., no interference between the transverse tracks of multiple half-wave plates), coordinated control commands are issued to the drive mechanism.

[0104] The visual monitoring interface includes real-time display of the current state vector, target state vector, and motion trajectory curves of each half-wave plate. It supports manual intervention to select "efficiency priority" or "life priority" mode and adjust the multi-objective optimization weights.

[0105] Through parallel motion planning, the switching time of an n-level optical path is shortened from the O(n) level of traditional serial control (e.g., 300ms for level 3) to O(1) level (≤100ms), meeting the real-time requirements of high-speed laser processing equipment (e.g., microelectronics cutting scenarios with 1000 wavelength switches per minute). By optimizing the motor acceleration and deceleration curves and start-stop strategies, wear on the servo motor gearbox and linear motor guide rails is reduced. After 100,000 switching cycles, the failure rate of the drive mechanism in the traditional solution was 15%, while this embodiment has been reduced to less than 5%. The mechanical interference problem that may be caused by the movement of multiple half-wave plates in cascade expansion (e.g., the spacing between adjacent half-wave plates on the lateral movement track is too close) is resolved. Through state-space modeling and conflict detection algorithms, stable operation is ensured when expanding to more than five optical paths.

[0106] In some embodiments, a multimodal sensor system is integrated into the front end of the processing head: a spectral sensor (1nm resolution) that collects the surface reflectance spectrum of the processed material in real time to identify the material type (such as copper, aluminum, ceramic, or polymer); a visual camera (120 frames per second) that uses images to identify the processing area and determine the processing process (cutting, welding, or marking); and a temperature sensor that monitors the real-time temperature of the processing area and provides feedback to the wavelength configuration algorithm. The electronic control system incorporates a built-in working condition self-identification neural network based on the ResNet architecture, which takes in spectral data, visual images, and temperature signals and outputs the optimal wavelength combination and light intensity ratio.

[0107] Configuration strategy generation process: Offline knowledge base construction: Experiments were conducted on over 100 material-process combinations, recording the optimal wavelength configuration for each working condition (e.g., stainless steel cutting requires double-harmonic frequency light with 15% fundamental frequency light for heat dissipation assistance; glass marking requires triple-harmonic frequency light with high energy density). This knowledge base was then built containing over 50,000 data points. This knowledge base was then fed into the twin model to simulate the effects of different wavelength combinations on processing quality (e.g., heat-affected zone size and edge roughness), generating a library of pre-optimized configurations.

[0108] Online real-time control: Multimodal sensors collect data in real time, pre-process it, and then input it into the working condition self-identification network. Within 10ms, the target wavelength set (e.g., {λ / 2, λ / 3}) and light intensity ratio (e.g., 6:4) corresponding to the current material-process are output. The electronic control system calls the adaptive algorithm of Example 1 to drive the half-wave plate to the target state and simultaneously triggers the temperature control system of the corresponding frequency-doubling optical path (e.g., preheating the frequency-doubling crystal constant temperature box to the optimal operating temperature). During processing, if the spectral sensor detects a change in material composition (e.g., the substrate is exposed after the oxide layer on the aluminum alloy surface is removed), the system automatically switches to the pre-stored substrate material configuration without manual intervention.

[0109] Self-evolution capability is achieved: After each processing is completed, the actual processing effect (edge ​​accuracy through visual detection and material modification depth through spectral detection) is compared with the preset target. If the deviation exceeds the threshold (such as ±5%), the working condition data is automatically added to the training set, and the neural network model is updated offline every 24 hours to continuously optimize the configuration strategy.

[0110] This system completely changes the traditional laser wavelength configuration model that relies on manual experience. Through multimodal perception and self-identification algorithms, it realizes a fully automatic process of "material input - wavelength self-matching", which is particularly suitable for multi-variety small-batch processing scenarios (such as personalized medical device manufacturing), and reduces operator training costs by 90%. Based on twin model pre-optimization and real-time working condition feedback, it automatically fine-tunes the wavelength ratio for different batches of the same material (such as copper alloys of different purities), reducing the processing defect rate from 8% of the traditional solution to below 2%, meeting the high reliability requirements of fields such as aerospace. Through a self-evolution mechanism, the system can autonomously learn newly developed processing technologies (such as laser micro-nanostructuring of new composite materials) without waiting for manufacturer software upgrades, significantly shortening the implementation cycle of new processes (from the traditional weeks to 24 hours).

[0111] In some embodiments, a full physical model of the device is built using the ANSYS Optics module and MATLAB / Simulink. This model includes: an optical sub-model that simulates the polarization state evolution of fundamental frequency light passing through a half-wave plate and polarizing lens, and the nonlinear conversion efficiency of the frequency-doubling crystal (accounting for the effects of temperature and crystal life); a mechanical sub-model that models the torque-displacement relationship of the servo motor-synchronous belt drive system, and the change in the linear motor's guideway friction coefficient (which increases with age); and an electronic control sub-model that maps the signal delay and sensor noise characteristics of the control module. The model is calibrated using real-time sensor data (temperature, motor current, and light intensity), with an error of ≤2%.

[0112] The predictive maintenance algorithm includes drive mechanism life prediction: Servomotor current waveforms and synchronous belt tension sensor data are collected and fed into an LSTM neural network to train a "motor load-wear degree" prediction model. This provides 72-hour advance warning of faults such as belt breakage and bearing wear. If the model predicts a remaining life of less than 10%, a maintenance work order is automatically generated, prompting component replacement and adjusting the control strategy (for example, reducing the half-wave plate adjustment speed to avoid sudden failures).

[0113] Energy optimization strategies include using a digital twin model to simulate the standby states of different frequency-doubled optical paths during non-processing periods (such as between material changes). If doubled frequency light is expected to be used within the next 30 minutes, the frequency-doubled crystal incubator for that optical path will remain operational (power consumption: 50W), while other optical paths will enter hibernation (power consumption: 5W). The model calculates the optimal standby combination, reducing overall energy consumption by 40% compared to the traditional all-standby mode. When multiple wavelengths are output simultaneously, the optical sub-model optimizes the half-wave plate angle, selecting the angle with the highest crystal conversion efficiency while maintaining a consistent light intensity ratio (e.g., avoiding the temperature-sensitive region of the crystal's nonlinear coefficient), improving electro-optical conversion efficiency by over 15%.

[0114] The virtual-reality interactive interface allows operators to view the real-time operating status of the digital twin through a 3D visualization interface, manually trigger virtual adjustments (such as simulating the impact of half-wave plate angle changes on light intensity), and assist in troubleshooting and parameter debugging.

[0115] By using the LSTM model to identify the deterioration trend of mechanical components in advance, traditional post-repair maintenance is transformed into preventive maintenance, which has been measured to reduce unplanned downtime by 80%. This is particularly suitable for industrial production lines that operate continuously 24 / 7.

[0116] Combining the digital twin's standby optimization and efficiency improvement strategies, the system achieves approximately 30% electricity savings compared to traditional devices (approximately 20,000 yuan annually, based on an industrial electricity price of 1 yuan per kWh) with an annual operation of 8,000 hours. From model calibration during the initial equipment commissioning phase to strategy adjustments during the aging phase, the digital twin continuously optimizes control parameters, ensuring the device maintains over 85% of its initial wavelength conversion efficiency after five years of operation, extending its service life by 20%.

[0117] In some embodiments, a reinforcement learning architecture is designed: The agent is responsible for dynamically adjusting the angles of each half-wave plate and the activation state of the frequency-doubling optical path, outputting control signals to the electronic control system. The state space includes over 50 parameters, including the current processing progress (obtained via a visual sensor), output light intensity at each wavelength, frequency-doubling crystal temperature, and motor operating status. The action space includes over 20 controllable actions, including half-wave plate angle adjustment (0.1° steps), frequency-doubling optical path start / stop (binary states), and cooling system power adjustment (10% steps). The reward function is designed based on a piecewise linear reward function, combining processing efficiency (processing area per unit time), quality indicators (e.g., a slit width deviation <5μm is worth +10 points, >10μm is worth -50 points), and energy consumption (-1 point per kilowatt-hour).

[0118] The online training and application process includes a pre-training phase: 100,000 machining simulations are performed in a virtual machining environment. The agent uses an ε-greedy strategy to explore the action space and learn the optimal wavelength combination strategy for different working conditions (for example, prioritizing double-frequency light intensity during high-speed cutting and balancing multi-wavelength heat input during precision welding). The Proximal Policy Optimization (PPO) algorithm is used to update the neural network parameters, gradually improving the reward function value by over 30%.

[0119] During the online application phase, the agent collects status data every 20ms during machining, generating action commands (e.g., "Increase the half-wave plate angle by 3.2°, activate the tripled frequency optical path cooling system") through a deep neural network. If an extreme operating condition not covered by pre-training is encountered (e.g., sudden strong light interfering with a sensor), a "safety mode" is triggered: the reinforcement learning control is temporarily frozen and the rule-based PID control is switched to prevent machining accidents. After each machining task is completed, the actual reward value is fed back to the training module to update the agent's strategy, forming a closed loop of "machining-learning-optimization."

[0120] Hardware collaborative optimization includes: adding a fast optical shutter (response time ≤ 1μs) in the frequency-doubling optical path, and coordinating it with high-frequency action instructions through reinforcement learning to achieve nanosecond-level timing control of multi-wavelength output (such as alternating output of doubled and tripled frequency light with an interval of 50ns), meeting the needs of ultra-high-speed micromachining.

[0121] Breaking through the limitations of traditional fixed-parameter machining, the intelligent agent uses reinforcement learning to automatically discover optimal wavelength combination strategies that are difficult for human engineers to detect (for example, on a specific material, when the second harmonic frequency light intensity accounts for 68% and the triple frequency accounts for 32%, the cutting speed increases by 12% and the edge is burr-free), achieving "machine-independent process innovation." By combining safety modes with rule-based control, stable machining is ensured even under abnormal conditions such as sensor noise and power grid fluctuations, reducing the failure rate by 60% compared to pure AI control solutions. Supporting a full range of applications, from micron-level precision marking (requiring nanosecond wavelength switching) to millimeter-level high-speed cutting (requiring hundreds of watts of light output), the intelligent agent dynamically adjusts control accuracy through reinforcement learning, allowing a single machine to cover a variety of processing needs and increasing equipment utilization by over 50%.

[0122] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A laser wavelength conversion device, characterized in that: include: Polarizing lens, used for polarizing and splitting the incident light beam, when the incident light beam is horizontally polarized, it passes through the polarizing lens, and when the incident light beam is vertically polarized, it is reflected on the light-facing surface of the polarizing lens; At least one half-wave plate is disposed on the incident light path of the polarizing lens, the half-wave plate being connected to an electronic control system, the electronic control system being used to control the half-wave plate to move laterally into or out of the light path, or to control the angle of the half-wave plate; At least two frequency-doubling optical paths, each corresponding to a different wavelength conversion requirement, the frequency-doubling optical path being connected to the transmission optical path or the reflection optical path of the polarizing lens; Wherein, the fundamental frequency light serves as the incident light beam. When the electric control system controls the half-wave plate not to be moved laterally into the optical path, the fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and is reflected into the first frequency-doubling optical path, and outputs frequency-doubling light of the corresponding wavelength. When the electric control system controls the half-wave plate to be moved laterally into the optical path, the polarization state of the fundamental frequency light changes, and the fundamental frequency light is incident on the polarizing lens in a horizontal linear polarization state and is transmitted into the next-stage optical path. If subsequent half-wave plates and polarizing lenses are provided in the next-stage optical path, the electric control system further controls the subsequent half-wave plates to be moved laterally into the optical path or to adjust the angle, so that the fundamental frequency light is incident on the subsequent polarizing lens in a corresponding polarization state, and is reflected or transmitted into the second frequency-doubling optical path and the third frequency-doubling optical path, and outputs frequency-doubling light of the corresponding wavelength. The electronic control system integrates a polarization state and wavelength mapping control module, which pre-stores the correspondence between different half-wave plate positions / angles and output wavelengths. When receiving a wavelength switching or multi-wavelength output instruction, the electronic control system automatically calculates and controls the lateral movement path or rotation angle of the half-wave plate, allowing the fundamental frequency light to accurately enter the target frequency-doubled optical path through polarization splitting. This avoids the cumulative errors of traditional mechanical adjustment and achieves high-precision control of wavelength conversion and millisecond-level fast switching. By adding a motion trajectory sensor to each half-wave plate drive mechanism in the cascade frequency doubling optical path, the lateral speed, acceleration, start-stop time are collected in real time; the electronic control system integrates a multi-objective optimization processor, supports non-dominated sorting genetic algorithm and dynamic programming algorithm, and handles the problem of multi-stage half-wave plate collaborative control; the objective function definition includes the shortest switching time: the maximum value of the action time of all half-wave plates; the minimum mechanical loss: the loss integral is calculated according to the number of motor starts and stops and the acceleration change rate; the optical path collimation is maintained: the half-wave plate angle adjustment range is constrained to avoid exceeding 90° and causing polarization state reversal error; state space modeling is achieved through By defining the state of each half-wave plate as a discrete variable, a state vector containing a multi-level optical path is constructed, and the target wavelength combination corresponds to a unique legal state vector; the switching path planning process includes calculating the difference between the current state vector and the unique legal state vector when a wavelength switching instruction is received, and determining the set of half-wave plates that need to be moved; the linear motors and servo motors in the half-wave plate set are grouped according to their motion characteristics; calling the non-dominated sorting genetic algorithm to generate a Pareto optimal solution set, finding a balance between switching time and mechanical loss, and after the final path is verified to have no mechanical conflict through dynamic planning, sending a collaborative control instruction to the drive mechanism.

2. The device according to claim 1, characterized in that When a servo motor and a synchronous belt are used in combination to control the angle of the half-wave plate, the fundamental frequency light adjusts the polarization angle between 0° and 90°, so that the intensity of the light incident on the polarized lens is transmitted and reflected proportionally, thereby achieving simultaneous output of multiple wavelengths, and the intensity ratio of each wavelength can be freely edited by the electronic control system.

3. The device according to claim 1, characterized in that The laser wavelength conversion device changes the polarization state of the fundamental frequency light by adjusting the position or angle of the half-wave plate through the electronic control system. After being split by the polarizing lens, the light enters the corresponding frequency doubling optical path, thereby realizing rapid switching or simultaneous output of different wavelengths.

4. The device according to claim 1, characterized in that The corresponding convertible wavelength is increased by adding a corresponding frequency doubling optical path and a half-wave plate polarization adjustment structure.

5. The device according to claim 1, characterized in that The fundamental frequency light is incident on the polarizing lens in a vertical linear polarization state and reflected into the first frequency-doubled optical path, and outputs frequency-doubled light of the corresponding wavelength, including: When the half-wave plate is not moved laterally into the optical path, the initial polarization state of the fundamental frequency light is vertical linear polarization. After being incident on the light-facing surface of the polarizing lens, it is reflected, and the reflected light path is connected to the input end of the first frequency doubling optical path. A frequency doubling crystal is provided in the first frequency doubling optical path. After the fundamental frequency light is converted by the frequency doubling crystal, the frequency doubled light of the corresponding wavelength is output.

6. The device according to claim 1, characterized in that When the electric control system controls the half-wave plate to move laterally into the optical path, the polarization state of the fundamental frequency light changes, including: The half-wave plate is driven by a linear motor to move horizontally into the incident light path. After the fundamental frequency light passes through the half-wave plate, its polarization state is converted from vertical linear polarization to horizontal linear polarization. When the horizontal linear polarization light is incident on the polarizing lens, it is directly transmitted through. The transmitted light path is connected to the input end of the next-level optical path, and the next-level optical path includes a subsequent frequency doubling optical path or a polarization splitting structure.

7. The device according to claim 1, characterized in that If a subsequent half-wave plate and a polarizing lens are provided in the next-stage optical path, the electronic control system further controls the subsequent half-wave plate to move laterally into the optical path or adjust the angle so that the fundamental frequency light is incident on the subsequent polarizing lens in the corresponding polarization state and is reflected or transmitted into the second and third frequency-doubled optical paths, and outputs frequency-doubled light of corresponding wavelengths, including: The subsequent half-wave plate is connected to the electronic control system. When the fundamental frequency light is transmitted through the preceding polarizing lens in a horizontally polarized state, if the electronic control system controls the subsequent half-wave plate to move horizontally into the optical path, the polarization state of the fundamental frequency light is changed to vertically polarized light again. When the fundamental frequency light is incident on the subsequent polarizing lens, it is reflected and enters the second frequency-doubling optical path. After being converted by the frequency-doubling crystal in the second frequency-doubling optical path, it outputs tripled frequency light. If the subsequent half-wave plate is not moved laterally into the optical path, the fundamental frequency light is transmitted through the subsequent polarizing lens in a horizontally linear polarized state and is directly output.

8. The device according to claim 1, characterized in that The drive mechanism of the half-wave plate includes a combination of a servo motor and a synchronous belt. The servo motor is linked to the half-wave plate via the synchronous belt, so that the half-wave plate can freely adjust the polarization adjustment angle within the range of 0° to 90°. After being adjusted by the half-wave plate, the fundamental frequency light is incident on the polarizing lens in a linear polarization state at any angle, so that the ratio of the transmitted light intensity to the reflected light intensity can be precisely controlled by the electronic control system, thereby achieving the simultaneous output of at least two light beams of different wavelengths in a preset ratio.

9. The device according to claim 1, characterized in that The number of frequency-doubling optical paths can be expanded in a cascade manner. Each level of the frequency-doubling optical path includes an independent half-wave plate, a polarizing lens, and a frequency-doubling crystal. The electronic control system controls the lateral shift state or angle of each half-wave plate step by step, so that the fundamental frequency light undergoes multiple levels of polarization splitting in sequence and then selectively enters the corresponding frequency-doubling optical path, thereby achieving scalable output of multiple wavelengths of doubled, tripled, and quadrupled frequency light. No additional optical switches or complex mechanical structures are required during the expansion process.

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