A feedback high-precision laser light splitting path system

Abstract

The application discloses a feedback type high-precision laser light splitting path system, and the system comprises a first light splitting device, a feedback type AOM secondary power stabilizing device, an AOM small-angle separating device and an MCU microprocessor controller; wherein the first light splitting device is used for changing the polarization direction of a laser beam through the rotation of a 1 / 2 wave plate, and then separating the beams with different polarization directions by using a polarization beam splitter, so that the power of a sub-path is flexibly adjusted to 0-100%; the feedback type AOM secondary power stabilizing device is used for taking an AOM as a secondary sub-path power controller, combining a PID control algorithm, dynamically and real-timely adjusting the diffraction efficiency of the AOM according to the feedback value measured by a photoelectric power meter, and stabilizing the sub-path power; the AOM small-angle separating device is used for separating the 0-order light and the 1-order light generated by the AOM diffraction based on the total internal reflection principle; and the MCU microprocessor controller is used for controlling the first light splitting device and the feedback type AOM secondary power stabilizing device. The application can efficiently split a single high-power laser, and has high practical value.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a feedback-type high-precision laser beam splitting optical path system. Background Technology

[0002] With the continuous development of the laser processing field, the simultaneous processing of large-format materials by multiple laser heads has become a trend. However, using multiple lasers simultaneously significantly increases costs, thus requiring in-depth research on how to split a single high-power laser beam. Furthermore, while the power stability of many high-power lasers is generally controlled within 3%, many sensitive materials are extremely sensitive to laser power. Ensuring the power stability of sub-optical paths also necessitates further research. The laser's own power adjustment precision cannot meet the processing accuracy requirements; when the actual power used is less than 10% of the laser's power, the laser's power stability is poor, and fluctuations in laser power during processing can cause processing defects in some sensitive materials. Therefore, laser beam splitting and power stability control of sub-optical path systems are indispensable technologies in laser micro-precision machining. Summary of the Invention

[0003] The present invention aims to solve the problems of high cost, poor power stability of lasers themselves under low percentage power use, and insufficient power stability of sub-optical paths in the prior art.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A feedback-type high-precision laser beam splitting optical path system includes: a primary beam splitting device, a feedback-type AOM secondary power stabilization device, an AOM small-angle separation device, and an MCU microprocessor controller;

[0006] The primary beam splitter is used to change the polarization direction of the laser beam by rotating the half-wave plate, and then uses a polarizing beam splitter to separate beams with different polarization directions, so as to achieve flexible adjustment of the sub-optical path power from 0 to 100%.

[0007] The feedback-type AOM secondary power stabilization device is used to use the AOM as a secondary sub-optical path power controller, combined with a PID control algorithm, to dynamically and in real time adjust the diffraction efficiency of the AOM based on the feedback value measured by the photoelectric power meter, thereby stabilizing the sub-optical path power.

[0008] The AOM small-angle separation device is used to separate the 0th-order light and the 1st-order light generated by AOM diffraction based on the principle of total internal reflection.

[0009] The MCU microprocessor controller is used to control the primary beam splitter and the feedback-type AOM secondary power stabilization device.

[0010] Furthermore, the primary beam splitter includes a half-wave plate and a polarizing beam splitter. The half-wave plate is placed in a hollow rotating platform. The MCU microprocessor controller drives the hollow rotating platform to rotate the half-wave plate by controlling the hollow platform motor controller, thereby changing the polarization direction of the laser beam and causing the distribution of laser beams in different polarization directions to change. Then, the polarizing beam splitter separates the polarized beams in different XY directions, realizing the adjustment of sub-optical path power from 0-100%.

[0011] Furthermore, the feedback-type AOM secondary power stabilization device includes an AOM diffracting device, an ultrasonic driver device, a digital-to-analog converter, a photoelectric power meter, and a partially reflective mirror with a coating. The partially reflective mirror with a coating is used to separate a small portion of the laser. The digital-to-analog converter is used to control the output intensity of the ultrasonic driver device with voltage. The photoelectric power meter is used to measure the power of this portion of the laser and transmit the data to the MCU microprocessor controller. The MCU microprocessor controller runs a PID control algorithm.

[0012] Furthermore, the PID control algorithm is specifically as follows:

[0013]

[0014] In the formula, K p For proportional gain, K p It is inversely proportional to the scale; T t T is the integration time constant; D is the differential time constant; u(t) is the output signal of the PID controller; e(t) is the difference between the given value r(t) and the measured value.

[0015] Furthermore, the AOM small-angle separation device includes two right-angle prisms with refractive indices, which form a cube with an air gap. The refractive index of the right-angle prisms is 1.51680@587.56nm.

[0016] Furthermore, the surface of the mirror lens of the coated part is coated with a 45° film layer with 95% high transmittance and 5% high reflectance.

[0017] Furthermore, the MCU microprocessor controller drives the hollow rotating platform to rotate the half-wave plate by controlling the hollow platform motor controller, thereby controlling the first-stage beam splitter; at the same time, it receives power data transmitted by the photoelectric power meter, runs the PID control algorithm, and controls the ultrasonic driver device through the digital-to-analog converter, thereby controlling the feedback AOM second-stage power stabilization device and coordinating the collaborative work of each device.

[0018] Furthermore, in the AOM small-angle separation device, the air gap formed by the two right-angle prisms is 125μm.

[0019] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0020] This invention can split a single high-power laser, reducing the cost of using multiple lasers; the first-stage splitting device can flexibly adjust the sub-optical path power from 0-100%, reducing power loss; the second-stage AOM feedback adjustment device can dynamically stabilize the sub-optical power in real time, meeting the processing requirements of sensitive materials; the separation device based on the principle of total internal reflection solves the problem of AOM diffraction light separation, which is conducive to achieving equipment compactness. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 Here is a flowchart of the PID control algorithm;

[0023] Figure 2 A three-dimensional diagram of a feedback-based high-precision laser beam splitting optical path system;

[0024] Figure 3 It is a high-angle resolution beam splitter with total internal reflection.

[0025] 1-Laser, 2-Mirror, 3-1 / 2 waveplate, 4-PBS polarizing beam splitter, 5-AOM, 6-Prism, 7-Coated partial mirror, 8-Photoelectric power meter, 9-Brass block, 10-MCU microprocessor, 11-Digital-to-analog converter (DAC), 12-Ultrasonic drive device (RF Drier), 13-Hollow platform motor controller, 14-Hollow rotating platform, A-First-order incident beam, B-First-order sub-beam exit beam, C-First-order residual exit beam, D-0th-order beam of AOM, E-1st-order beam of AOM. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This feedback-based high-precision laser beam splitting optical path system includes a primary beam splitting device, a feedback-based AOM secondary power stabilization device, AOM level 0 and 1 small-angle separation devices, and an MCU microprocessor controller.

[0028] The primary beam splitter uses a 1 / 2 waveplate + PBS configuration. Rotating the 1 / 2 waveplate changes the polarization direction of laser beam A, altering the distribution of laser beams with different polarization directions. A polarizing beam splitter then separates the beams B and C, which are polarized in different XY directions. Waveplate 3 is placed in a hollow rotating platform 14. An MCU microcontroller 10 controls a motor controller 13 to drive the hollow rotating platform 14, rotating the waveplate to control the laser power of sub-beam B from 0-100%. The remaining laser C is then separated into a second sub-beam using the same method. Compared to beam splitting methods using coated lenses with fixed transmittance, this method significantly reduces laser power loss and allows for flexible control of laser on / off states when controlling the power of a single beam, achieving 0-100% power control for a single laser beam.

[0029] The feedback-type AOM (Optical Oscillator) secondary power stabilization device, using a 1 / 2 waveplate + PBS (Polarization-Based Photodiode), can effectively separate sub-beams, but it struggles to stabilize their power. This is primarily due to the weak response of the hollow rotating platform 14, and the rapid rotation can negatively impact the power of subsequent sub-beams. Therefore, an AOM is used as the secondary sub-beam power controller. As a diffraction device, the AOM offers advantages such as fast control response and a wide power control range. While the AOM can control diffraction efficiency to control power, it doesn't know whether to increase or decrease the power. Therefore, in automatic control, feedback values ​​are obtained by monitoring the final output. These feedback values ​​are then used to adjust the control state of the preceding stage in real time to achieve stable output; this control is also known as closed-loop regulation. There are many ways to ensure the real-time value reaches the set target value. One common method in industrial control is the PID (Proportional-Integral-Derivative) control algorithm, which, in process control, uses the proportional (P), integral (I), and derivative (D) functions of the deviation. The essence of PID control is to calculate the input deviation value according to the proportional, integral, and derivative functional relationship, and then use the result to control the output.

[0030] In industrial processes, the ideal PID control law for a continuous control system is as follows:

[0031]

[0032] In the formula, K p —Proportional gain, K p It is inversely proportional to the scale.

[0033] T t —Integral time constant;

[0034] T D —Differential time constant;

[0035] u(t) — Output signal of the PID controller;

[0036] e(t) — the difference between the given value r(t) and the measured value.

[0037] Closed-loop control This control method uses feedback from the controlled object's output for correction. When a deviation is detected between the actual and planned output, corrections are made according to quotas or standards. For obtaining the feedback value, a small portion of the laser light is separated by a partially coated mirror 7 (the mirror surface is coated with a 95% high-transmittance, 5% high-reflectance 45° film). Power is measured by a photoelectric power meter 8, and the power data is transmitted to the microcontroller chip (MCU) to run a PID algorithm to control the diffraction efficiency of the AOM, thereby controlling the laser power. The secondary optical power control component mainly consists of an analog-to-digital converter 11, an ultrasonic driver device 12, and an AOM diffracting device 5. The diffraction behavior of the AOM relies primarily on ultrasound. Ultrasound propagation in a crystal causes periodic changes in the crystal's refractive index, resulting in diffraction of the incident light—a phenomenon known as the acousto-optic effect. According to the formula, a certain ultrasonic frequency value can maximize the diffraction efficiency of the AOM. Therefore, the diffraction efficiency of the AOM can be controlled by controlling the amplitude intensity of the ultrasonic wave (0-5V). In order to improve the control accuracy of the RF DRIVER ultrasonic driver device, an analog-to-digital converter is used as the voltage control output. The 10-bit width can realize up to 1024 control values ​​at a maximum voltage of 5V.

[0038] The AOM (Area-Order Optimal Beam) beam splitter for separating 0th and 1st order beams at small angles achieves the highest diffraction efficiency at the optimal Bragg diffraction angle. However, the optimal Bragg diffraction angle is still very small (less than 50 mrad), making it difficult to separate 0th and 1st order beams over short distances. This requires extending the beam over a long distance and then blocking the 1st order beam to retain the 0th order beam. However, it's difficult to reserve enough space in laser processing equipment, and a longer optical path sacrifices equipment compactness and increases adjustment difficulty. A high-angle-resolution beam splitter based on total internal reflection is employed to separate superimposed beams that differ only in angle. Its operating principle relies entirely on the angle of total internal reflection. Since the wavelength dependence of the device stems solely from the wavelength dependence of the anti-reflective (AR) coating, and the optical elements rely only on standard optical components, the wavelength and element size can be easily adjusted to meet the requirements of various applications.

[0039] After passing through the AOM (Alternating Optical Array), the laser beam undergoes diffraction, splitting into 0th-order and 1st-order beams. Figure 3On the right, two right-angled prisms with a refractive index n1 (n1 = 1.51680 @ 587.56 nm) form a cube with an air gap (125 μm) (the refractive index of air n2 < n1), where total internal reflection can occur at the air gap. When tuned to the critical angle, a beam of one diffraction order reaches the total reflection condition and is reflected, while the other is transmitted through the beam splitter. To separate the beams of different diffraction orders, the beam splitter must be tuned to the critical angle of total internal reflection so as to reflect a beam of one diffraction order and refract a beam of another diffraction order according to Snell's law. When entering the second prism, the beam is refracted again in the original propagation direction and passes through the optical element. When a beam of one diffraction order is completely reflected (independent of polarization), the transmitted beam is not only refracted but also reflected according to Fresnel's equations when leaving the first prism and entering the second prism. Such a beam splitter can be used to develop a compact laser system module, which is very suitable for highly stable laser systems for space or other field applications.

[0040] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference may be made to each other.

[0041] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the core idea of the present invention; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A feedback-based high-precision laser beam splitting optical path system, characterized in that, The system includes: The device includes a primary beam splitter, a feedback-type AOM secondary power stabilization device, an AOM small-angle separation device, and an MCU microprocessor controller. The primary beam splitter is used to change the polarization direction of the laser beam by rotating the half-wave plate, and then uses a polarizing beam splitter to separate beams with different polarization directions, so as to achieve flexible adjustment of sub-optical path power from 0 to 100%. The primary beam splitter includes a half-wave plate and a polarizing beam splitter. The half-wave plate is placed in a hollow rotating platform. The MCU microprocessor controller drives the hollow rotating platform to rotate the half-wave plate by controlling the hollow platform motor controller, thereby changing the polarization direction of the laser beam and causing the distribution of laser beams in different polarization directions to change. Then, the polarizing beam splitter separates the polarized beams in different XY directions, realizing the adjustment of sub-optical path power from 0-100%. The feedback-type AOM secondary power stabilization device is used to use the AOM as a secondary sub-optical path power controller, combined with a PID control algorithm, to dynamically and in real time adjust the diffraction efficiency of the AOM based on the feedback value measured by the photoelectric power meter, thereby stabilizing the sub-optical path power. The feedback-type AOM secondary power stabilization device includes an AOM diffractometer, an ultrasonic driver, a digital-to-analog converter, a photoelectric power meter, and a partially reflective mirror with a coating. The partially reflective mirror is used to separate a small portion of the laser beam. The digital-to-analog converter is used to control the output intensity of the ultrasonic driver with voltage. The photoelectric power meter is used to measure the power of this portion of the laser beam and transmit the data to the MCU microprocessor controller. The MCU microprocessor controller runs a PID control algorithm. The AOM small-angle separation device is used to separate the 0th-order light and the 1st-order light generated by AOM diffraction based on the principle of total internal reflection; The MCU microprocessor controller is used to control the first-stage beam splitter and the feedback-type AOM second-stage power stabilization device; The MCU microprocessor controller drives the hollow rotating platform to rotate the half-wave plate by controlling the hollow platform motor controller, thereby controlling the first-stage beam splitter. At the same time, it receives power data transmitted by the photoelectric power meter, runs a PID control algorithm, and controls the ultrasonic driver through a digital-to-analog converter, thereby controlling the feedback AOM second-stage power stabilization device and coordinating the work of each device.

2. The feedback-type high-precision laser beam splitting optical path system according to claim 1, characterized in that, The PID control algorithm is as follows: In the formula, For proportional gain, It is inversely proportional to the scale. The integral time constant; The differential time constant; This is the output signal of the PID controller; The difference between the given value r(t) and the measured value.

3. The feedback-type high-precision laser beam splitting optical path system according to claim 1, characterized in that, The AOM small-angle separation device includes two right-angle prisms with refractive indices, which form a cube with an air gap. The refractive index of the right-angle prisms is 1.51680 at a laser wavelength of 587.56 nm.

4. The feedback-type high-precision laser beam splitting optical path system according to claim 1, characterized in that, The surface of the mirror with the coating is coated with a 45° film layer that has 95% high transmittance and 5% high reflectance.

5. The feedback-type high-precision laser beam splitting optical path system according to claim 1, characterized in that, In the AOM small-angle separation device, the air gap formed by the two right-angle prisms is 125μm.

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