Electric power adjusting mechanism of wafer laser trimming equipment

Abstract

The application relates to the technical field of semiconductor laser processing equipment, in particular to an electric power adjusting mechanism of a wafer laser trimming device, which comprises a base, a pedestal, an air gap zero-order wave plate, a driven hollow synchronous pulley, a stepping motor, a power transmission chain and an electric control module. The electric control module comprises a data acquisition unit, a basic scheme generation unit, a first correction unit, a second optimization unit, a zero-point calibration unit and an execution driving unit. Deviation correction is carried out according to real-time power feedback, thermal expansion compensation is carried out according to temperature data, and the original point reference is automatically calibrated. Finally, the pulse signal is converted to drive the stepping motor to rotate the air gap zero-order wave plate, high-precision and continuous stepless electric adjustment of laser power is realized, the influence of temperature drift and mechanical error is effectively overcome, and the precision and long-term stability of wafer trimming are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser processing equipment technology, and in particular to an electric power adjustment mechanism for a wafer laser trimming device. Background Technology

[0002] In the field of wafer laser trimming equipment, precise control of laser power is one of the core aspects of ensuring system stability and operational accuracy. Traditional laser power adjustment schemes often employ methods such as attenuator stacking, mechanical aperture adjustment, or ordinary waveplates combined with polarization elements. However, attenuator stacking has drawbacks such as discrete power adjustment levels and the inability to achieve continuous stepless control. While mechanical aperture adjustment can change the aperture to control power, it disrupts the Gaussian distribution characteristics of the laser beam, leading to a decrease in beam quality and making it difficult to meet the requirements of high-precision optical applications.

[0003] For example, Chinese Patent CN207801140U discloses an electrically adjustable solid-state laser, including a laser cavity assembly for generating laser light and a laser output assembly composed of a total reflection mirror, a semi-reflecting mirror, and a beam expander. The total reflection mirror, laser cavity assembly, semi-reflecting mirror, and beam expander are sequentially arranged on a laser base. Both the total reflection mirror and the semi-reflecting mirror are mounted on the laser base via an adjustment frame, which includes: an outer frame fixed to the laser base; an inner frame movable up and down within the outer frame; and a mirror frame movable left and right within the inner frame, with a through hole in the middle. A first electromagnet push-pull device is provided between the outer frame and the inner frame to push the inner frame up and down, while a first spring group supports the elastic return of the inner frame. A second electromagnet push-pull device is provided between the inner frame and the mirror frame to push the mirror frame left and right, while a second spring group supports the elastic return of the mirror frame. Both the first and second spring groups include three springs arranged at equal intervals. However, this solution still suffers from low efficiency and poor accuracy of manual adjustment, as well as insufficient long-term stability due to the lack of temperature drift compensation. Summary of the Invention

[0004] To address this, the present invention provides an electric power adjustment mechanism for a wafer laser trimming device, which overcomes the problems of low efficiency, poor accuracy, and insufficient long-term stability caused by the lack of temperature drift compensation in the prior art.

[0005] To achieve the above objectives, the present invention provides an electric power adjustment mechanism for a wafer laser trimming device, comprising: Base; A base, which is connected to the pedestal; A polarizing beam splitter holder, which is connected to the base; A polarizing beam splitter, which is mounted on the polarizing beam splitter holder; Air gap zero-order waveplate; A driven hollow synchronous belt pulley, with the air gap zero-order waveplate fixed inside its hollow interior; The copper bearing bush is fixed to the two end faces of the driven hollow synchronous pulley, and the copper bearing bush is fixed to the base. Active synchronous pulley; A timing belt, wherein the driving timing pulley is connected to the driven hollow timing pulley via the timing belt; A drive shaft, which is connected to the drive synchronous pulley; A coupling that connects to the drive shaft; A speed reducer, which is connected to the coupling; A stepper motor is connected to the reducer, and the stepper motor, the reducer, the coupling, the drive shaft and the drive synchronous pulley are sequentially connected to form a power transmission chain; The tensioning pulley, which is mounted on the base, tensions the timing belt. A zero-point photoelectric switch is mounted on the base; A heat sink is mounted on the surface of the stepper motor; The electric control module, which is connected to the stepper motor, the zero-point photoelectric switch and the laser power meter, is used to acquire control status data, generate a target angle based on the control status data, perform power deviation correction on the target angle, perform temperature drift compensation during the power deviation correction process, obtain the target rotation angle, and control the stepper motor based on the target rotation angle.

[0006] Furthermore, the end of the air-gap zero-order waveplate furthest from the driven hollow synchronous pulley is arranged opposite to the polarizing beam splitter, with the laser incident direction sequentially passing through the air-gap zero-order waveplate and the polarizing beam splitter to form an optical attenuation path; the driven hollow synchronous pulley is mounted in the copper bearing bush via a precision bearing to provide low-friction rotational support; the copper bearing bush is used to establish a structural reference; the output shaft of the stepper motor is connected to the input end of the reducer to reduce the speed and increase the torque; the output end of the reducer is connected to one end of the drive shaft via the coupling to compensate for installation errors and transmit rotational motion; the end of the drive shaft furthest from the coupling is fixedly connected to the driving synchronous pulley to output driving force. The system comprises a drive synchronous pulley, a synchronous belt, and a driven hollow synchronous pulley, forming a reduction transmission chain that drives the air gap zero-order waveplate to rotate. A sensing element is fixed to the drive synchronous pulley to provide a position trigger mark. A zero-point photoelectric switch engages with the sensing element to detect the origin position and generate a reference signal. The electric control module is connected to the stepper motor's driver signal to output a pulse control signal. The electric control module is also connected to the zero-point photoelectric switch signal to obtain the origin reference position. Furthermore, the electric control module is connected to a laser power meter signal to collect real-time power feedback data. The power transmission chain drives the air gap zero-order waveplate to rotate to the target angle, thereby achieving electric adjustment of the laser power.

[0007] Furthermore, the copper bearing bush is made of brass, which has a coefficient of linear expansion of [value missing]. .

[0008] Furthermore, the tension force F applied by the tensioning pulley to the synchronous belt satisfies 20N≤F≤30N, and the thermal resistance Rth of the heat sink satisfies Rth≤2.5K / W.

[0009] Furthermore, the electric control module includes: The data acquisition unit is used to acquire control status data; The basic scheme generation unit is used to generate a basic target angle based on the target laser power value and the incident laser power value in the control state data; The first calibration unit is used to perform power deviation calibration on the basic target angle based on the real-time output power value in the control state data, and obtain the calibrated rotation angle. The second optimization unit is used to perform temperature drift compensation on the power deviation correction process based on the winding temperature value in the control state data to obtain the target rotation angle. The zero-point calibration unit is used to calibrate the origin reference position based on the trigger signal of the zero-point photoelectric switch and the relative position of the sensing element, so as to obtain the reference origin position. The execution drive unit is used to convert the target rotation angle and the reference origin position into pulse control signals, and control the stepper motor according to the pulse control signals, so as to drive the air gap zero-order waveplate to rotate through the power transmission chain.

[0010] Further, the basic scheme generation unit generates a basic target angle based on the target laser power value and the incident laser power value in the control state data, including: Calculate the target transmittance based on the target laser power value Pt and the incident laser power value Pi. ,set up And based on the target transmittance Tt and Malus's law, the theoretical rotation angle θt is calculated, and set The transmission coefficient K is calculated based on the reduction ratio Rg of the reducer and the step angle θs of the stepper motor, and K = θs / Rg is set. The basic target angle θb is also calculated based on the transmission coefficient K and the theoretical rotation angle θt, and θb = θt / K is set.

[0011] Further, the first calibration unit performs power deviation calibration on the basic target angle based on the real-time output power value in the control state data to obtain the calibrated rotation angle, including: The power deviation ΔP between the real-time output power value Pr and the target laser power value Pt is calculated, and ΔP = Pr - Pt is set. The power deviation ΔP is compared with the first preset tolerance value RC1 and the second preset tolerance value RC2. The degree of power deviation is judged based on the comparison result, and the power deviation of the basic target angle is corrected based on the judgment result. When RC1≤ΔP≤RC2, the first calibration unit determines that the power deviation level meets the standard and does not perform power deviation calibration on the basic target angle; When ΔP < RC1, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ. When ΔP > RC2, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ.

[0012] Further, the second optimization unit performs temperature drift compensation on the power deviation correction process based on the winding temperature value in the control state data to obtain the target rotation angle, including: The temperature deviation value ΔT is calculated based on the winding temperature value Tr and the reference temperature Tb, where ΔT = Tr - Tb. The temperature deviation value ΔT is then compared with a preset temperature drift value ΔTth. The significance of the temperature drift impact is judged based on the comparison result, and temperature drift compensation is performed during the power deviation calibration process based on the judgment result. Wherein: When ΔT≤ΔTth, the second optimization unit determines that the degree of influence of the temperature drift is not significant, and does not perform temperature drift compensation in the power deviation correction process; When ΔT > ΔTth, the second optimization unit determines that the degree of influence of the temperature drift is significant and performs temperature drift compensation on the power deviation calibration process: calculate the thermal expansion compensation amount Δθth according to the linear expansion coefficient α, and set Δθth = α × L × ΔT × Wm, where L is the effective length of the transmission shaft and Wm is the mechanical transmission error amplification coefficient. Then, perform temperature drift compensation on the calibration rotation angle θc according to the thermal expansion compensation amount Δθth to obtain the target rotation angle θm, and set θm = θc + Δθth.

[0013] Furthermore, the zero-point calibration unit controls the stepper motor to rotate at the origin-finding speed Vh. When the sensing element triggers the zero-point photoelectric switch to generate a falling edge signal, the current position is recorded as a temporary origin. The stepper motor is then controlled to rotate in the reverse direction to disengage a distance D. The stepper motor is then controlled to rotate in the forward direction again to approach the zero-point photoelectric switch at a low-speed origin-finding speed Vl. When the zero-point photoelectric switch is triggered again, the current mechanical position is calibrated as the reference origin position P0.

[0014] Further, the execution drive unit uses the reference origin position P0 as the origin of the absolute pulse coordinate system, calculates the target pulse position Pm based on the target rotation angle θm, the microstepping number N of the stepper motor, and the step angle θs, and sets Pm = θm × N / θs. It also calculates the number of pulses Np starting from the origin based on the coordinate difference between the target pulse position Pm and the origin of the absolute pulse coordinate system P0, sets Np = Pm - P0, and generates a pulse control signal based on the number of pulses. This signal controls the stepper driver to drive the stepper motor to rotate from the origin of the absolute pulse coordinate system P0 to the target pulse position Pm according to the number of pulses Np. The driven hollow synchronous pulley is rotated through the reducer, the coupling, the transmission shaft, the active synchronous pulley, and the synchronous belt, thereby driving the air gap zero-order waveplate to rotate to the target angle.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the base provides structural support and installation reference for the base and the polarizing beam splitter holder, ensuring the spatial positional stability of the optical elements and transmission components; the base supports the copper bearing, the tension wheel, and the zero-point photoelectric switch, providing a rigid mounting platform for the power transmission chain; the polarizing beam splitter holder provides a precision positioning mounting surface for the polarizing beam splitter, ensuring that the optical axis of the polarizing beam splitter is perpendicularly aligned with the optical axis of the air-gap zero-order waveplate; the polarizing beam splitter splits the laser beam modulated by the air-gap zero-order waveplate according to its polarization state, achieving attenuated laser power output; the air-gap zero-order waveplate is used to... Rotation changes the polarization direction of the emitted laser, enabling continuous stepless adjustment of laser power while maintaining the Gaussian distribution characteristics of the beam. The driven hollow synchronous pulley supports and fixes the air-gap zero-order waveplate through its hollow structure, driving it to rotate precisely under the synchronous belt, thus achieving angle adjustment. The copper bearing provides low-friction rotational support for the driven hollow synchronous pulley via precision bearings, limiting radial runout and ensuring that the rotational concentricity error of the air-gap zero-order waveplate is less than 5μm. The driving synchronous pulley receives the torque transmitted by the drive shaft and transmits the rotational motion to the driven hollow synchronous pulley via the synchronous belt, achieving speed reduction and torque increase. The transmission system includes: a synchronous belt for transmitting rotational motion between the driving synchronous pulley and the driven hollow synchronous pulley, absorbing vibration through elastic deformation to ensure transmission synchronicity; a transmission shaft for transmitting torque between the coupling and the driving synchronous pulley, bearing rotational loads; a coupling for compensating for installation coaxiality errors between the reducer output shaft and the transmission shaft, transmitting torque and protecting the reducer bearings; a reducer for reducing the output speed of the stepper motor, increasing output torque, and improving angle control resolution; and a stepper motor for providing precise step angle output based on the pulse control signal, driving the power transmission chain to rotate the air gap zero-stage waveplate to the target angle. The tensioning wheel applies constant tension to the synchronous belt, eliminating belt-side gaps and preventing relative slippage between the synchronous belt and the pulley. The zero-point photoelectric switch detects the position signal of the sensing plate and generates an origin trigger signal, providing an angular reference zero point for the air-gap zero-order waveplate. The heat sink reduces the winding temperature of the stepper motor through heat conduction, suppressing thermal expansion errors caused by temperature rise and ensuring angle control accuracy. The electric control module performs closed-loop control of the stepper motor, driving the air-gap zero-order waveplate to rotate, achieving high-precision and automated control of laser power, solving the problems of low efficiency, poor accuracy, and insufficient long-term stability caused by lack of temperature drift compensation in existing technologies. In particular, the electric control module automatically acquires the target laser power value, incident laser power value, real-time output power value, and winding temperature value in real time through the data acquisition unit, replacing manual reading and recording, eliminating delays and misreadings caused by human operation, improving the real-time performance and automation of power control, and solving the technical problem of low efficiency in manual adjustment; the electric control module also establishes a theoretical attenuation model based on Malus's law through the basic scheme generation unit, directly mapping the target power value to the theoretical rotation angle of the waveplate, realizing the quantitative automatic conversion of power-angle, eliminating the arbitrariness of manual estimation and table lookup calculation, providing a precise benchmark for subsequent closed-loop correction, and solving the technical problem of poor accuracy in manual adjustment; the electric control module also performs dynamic deviation correction of the theoretical rotation angle based on the real-time output power feedback value through the first calibration unit, constructing a power closed-loop control loop, eliminating power deviations caused by optical component installation errors, light source fluctuations, and mechanical transmission clearances in real time, ensuring that the actual output power is consistent with the target value, and solving the problem of poor accuracy caused by the inability to provide real-time feedback correction in manual adjustment; the electric control module The module also uses a second optimization unit to quantitatively compensate for the mechanical thermal expansion caused by temperature drift based on the winding temperature value. This adaptively corrects the difference in thermal expansion between the drive shaft and the copper bearing caused by temperature changes, suppresses angle drift during long-term operation, improves the long-term stability of the mechanism in variable temperature environments, and solves the problem of insufficient long-term stability caused by the lack of temperature drift compensation. The electric control module also uses a zero-point calibration unit to automatically calibrate the origin reference position, eliminating the cumulative error of stepper motor step loss and mechanical return backlash. This ensures that the angle reference is unique and repeatable after each power-on or reset, providing a reliable zero-point reference for the angle accuracy during long-term operation and solving the problem of difficulty in ensuring repeatable positioning accuracy during manual adjustment. The electric control module also uses an execution drive unit to convert the optimized target rotation angle into a high-precision pulse control signal, driving the stepper motor to drive the air gap zero-level waveplate to rotate precisely, realizing continuous stepless electric adjustment of laser power. This avoids the low efficiency and operational errors of manual waveplate rotation, improves the resolution and response speed of power adjustment, and solves the technical problems of low efficiency and poor accuracy of manual adjustment. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the electric power adjustment mechanism of the wafer laser trimming equipment in this embodiment; Figure 2 This is a front view of the electric power adjustment mechanism of the wafer laser trimming equipment in this embodiment; Figure 3 This is a top view of the electric power adjustment mechanism of the wafer laser trimming equipment in this embodiment; Figure 4 This is a right view of the electric power adjustment mechanism of the wafer laser trimming equipment in this embodiment; Figure 5This is a schematic diagram of the electric control module. Detailed Implementation

[0017] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0018] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0019] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0020] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] Please see Figures 1 to 4 The diagram shown is a structural schematic of the electric power adjustment mechanism of the wafer laser trimming equipment in this embodiment. The mechanism includes: Base 1; Base 2, which is connected to the base 1; Polarizing beam splitter holder 3, which is connected to the base 1; Polarizing beam splitter 4 is mounted on the polarizing beam splitter holder 3; Air gap zero-order waveplate 5; Driven hollow synchronous pulley 6, with the air gap zero-order waveplate 5 fixed inside its hollow interior; The copper bearing 7 is fixed on both ends of the driven hollow synchronous pulley 6, and the copper bearing 7 is fixed on the base 2. Active synchronous pulley 8; Synchronous belt 9, the driving synchronous pulley 8 is connected to the driven hollow synchronous pulley 6 through the synchronous belt 9; Drive shaft 10, which is connected to the drive synchronous pulley 8; Coupling 11, which is connected to the drive shaft 10; The speed reducer 12 is connected to the coupling 11; A stepper motor 13 is connected to the reducer 12. The stepper motor 13, the reducer 12, the coupling 11, the drive shaft 10 and the active synchronous pulley 8 are connected in sequence to form a power transmission chain. Tensioner 14, which is mounted on the base 2, tensions the timing belt 9. Zero-point photoelectric switch 15, which is mounted on the base 2; Heat sink 16 is mounted on the surface of the stepper motor 13; The electric control module 17 is connected to the stepper motor 13, the zero-point photoelectric switch 15, and the laser power meter. It is used to acquire control status data, generate a target angle based on the control status data, perform power deviation correction on the target angle, perform temperature drift compensation during the power deviation correction process, obtain the target rotation angle, and control the stepper motor 13 based on the target rotation angle.

[0022] Specifically, the electric power adjustment mechanism of the wafer laser trimming equipment is applied to the wafer laser trimming equipment for continuous stepless electric adjustment of the laser output power. The base 1 provides structural support and mounting reference for the base 2 and the polarization beam splitter mount 3, ensuring the spatial positional stability of the optical components and transmission parts. The base 2 supports the copper bearing 7, the tension wheel 14, and the zero-point photoelectric switch 15, providing a rigid mounting platform for the power transmission chain. The polarization beam splitter mount 3 provides a precision positioning mounting surface for the polarization beam splitter 4, ensuring that the optical axis of the polarization beam splitter 4 is perpendicularly aligned with the optical axis of the air gap zero-order waveplate 5. The polarization beam splitter 4 is used to... The laser beam modulated by the air-gap zero-order waveplate 5 is split according to its polarization state to achieve attenuated laser power output. The air-gap zero-order waveplate 5 is used to change the polarization direction of the emitted laser by rotation, and works with the polarization beam splitter 4 to achieve continuous stepless adjustment of the laser power while maintaining the Gaussian distribution characteristics of the beam. The driven hollow synchronous pulley 6 is used to support and fix the air-gap zero-order waveplate 5 through its hollow structure, and drives the air-gap zero-order waveplate 5 to rotate precisely under the drive of the synchronous belt 9, realizing the angle adjustment function. The copper bearing 7 is used to provide low-friction rotational support for the driven hollow synchronous pulley 6 through a precision bearing, limiting radial runout and ensuring that the rotational concentricity error of the air-gap zero-order waveplate 5 is less than 5%. μm; the active synchronous pulley 8 is used to receive the torque transmitted by the drive shaft 10, and transmits the rotational motion to the driven hollow synchronous pulley 6 through the synchronous belt 9 to achieve speed reduction and torque increase transmission; the synchronous belt 9 is used to transmit rotational motion between the active synchronous pulley 8 and the driven hollow synchronous pulley 6, and absorbs vibration through elastic deformation to ensure transmission synchronization; the drive shaft 10 is used to transmit torque between the coupling 11 and the active synchronous pulley 8, and bears rotational load; the coupling 11 is used to compensate for the installation coaxiality error between the output shaft of the reducer 12 and the drive shaft 10, transmit torque and protect the bearings of the reducer 12; the reducer 12 is used to reduce the speed of the stepper motor 13. The output speed is increased, the output torque is increased, and the angle control resolution is improved; the stepper motor 13 is used to provide a precise step angle output according to the pulse control signal, driving the power transmission chain to rotate the air gap zero-order waveplate 5 to the target angle; the tension wheel 14 is used to apply a constant tension force to the synchronous belt 9, eliminate belt side gap, and prevent relative slippage between the synchronous belt 9 and the pulley; the zero-point photoelectric switch 15 is used to detect the position signal of the sensing plate, generate an origin trigger signal, and provide an angle reference zero point for the air gap zero-order waveplate 5; the heat sink 16 is used to reduce the winding temperature of the stepper motor 13 through heat conduction, suppress thermal expansion error caused by temperature rise, and ensure angle control accuracy;The electric control module 17 performs closed-loop control on the stepper motor 13, driving the air gap zero-order waveplate 5 to rotate. This achieves high-precision, automated control of the laser power, solving the problems of low efficiency, poor accuracy, and insufficient long-term stability caused by the lack of temperature drift compensation in existing technologies.

[0023] Specifically, the end of the air-gap zero-order waveplate 5 furthest from the driven hollow synchronous pulley 6 is arranged opposite to the polarizing beam splitter 4, with the laser incident direction sequentially passing through the air-gap zero-order waveplate 5 and the polarizing beam splitter 4 to form an optical attenuation path; the driven hollow synchronous pulley 6 is mounted in the copper bearing 7 via a precision bearing to provide low-friction rotational support; the copper bearing 7 is fixed to the base 2 to establish a structural reference; the output shaft of the stepper motor 13 is connected to the input end of the reducer 12 to reduce speed and increase torque; the output end of the reducer 12 is connected to one end of the drive shaft 10 via the coupling 11 to compensate for installation errors and transmit rotational motion; the end of the drive shaft 10 furthest from the coupling 11 is fixedly connected to the driving synchronous pulley 8 to output driving torque. The active synchronous pulley 8 is connected to the driven hollow synchronous pulley 6 via the synchronous belt 9 to form a reduction transmission chain that drives the air gap zero-order waveplate 5 to rotate. The sensing plate is fixed on the active synchronous pulley 8 to provide a position trigger mark. The zero-point photoelectric switch 15 is fixed on the base 2 and cooperates with the sensing plate to detect the origin position and generate a reference signal. The electric control module 17 is connected to the driver signal of the stepper motor 13 to output a pulse control signal. The electric control module 17 is also connected to the zero-point photoelectric switch 15 to obtain the origin reference position. The electric control module 17 is also connected to the laser power meter to collect real-time power feedback data. The power transmission chain drives the air gap zero-order waveplate 5 to rotate to the target angle, thereby realizing the electric adjustment of the laser power.

[0024] Specifically, the precision bearing refers to a deep groove ball bearing with a precision grade of P5. It is installed in the bearing seat holes at both ends of the copper bearing bush 7 to provide radial support for the driven hollow synchronous pulley 6 and limit axial movement. In this embodiment, the copper bearing bush 7 is fixed to the base 2 by bolts. In other embodiments, the copper bearing bush 7 is integrally connected to the base 2 by a flange structure.

[0025] Specifically, the copper bearing 7 is made of brass, and its coefficient of linear expansion is [missing information]. .

[0026] Specifically, the tension force F applied by the tensioning pulley 14 to the synchronous belt 9 satisfies 20N≤F≤30N, the heat sink 16 is mounted on the surface of the stepper motor 13, and the thermal resistance Rth of the heat sink 16 satisfies Rth≤2.5K / W.

[0027] Specifically, the tension force F satisfies 20N≤F≤30N for the following reasons: When F<20N, meshing gaps easily occur between the synchronous belt 9 and the driving synchronous pulley 8 and the driven hollow synchronous pulley 6, leading to transmission errors and lag in angle transmission; when F>30N, the radial load on the bearing of the copper bearing 7 is too large, which easily leads to accelerated wear of the precision bearing and bending deformation of the transmission shaft 10, affecting the rotational concentricity of the zero-order waveplate 5 in the air gap. The thermal resistance value Rth satisfies Rth≤2.5K / W for the following reasons: According to the steady-state thermal balance equation ΔT=Ploss×Rth, where Ploss is the internal power loss of the stepper motor 13 during continuous operation, calculated at a rated operating condition of 10W, ensuring that the winding temperature rise ΔT of the stepper motor 13 is ≤25K, combined with an ambient temperature of 25℃, the total temperature is controlled within 50℃, avoiding the thermal expansion difference between the transmission shaft 10 and the copper bearing 7 exceeding 0.05mm, thus ensuring the accuracy of angle transmission.

[0028] Please see Figure 5 As shown, this is a schematic diagram of the structure of the electric control module 17 in this embodiment. The electric control module 17 includes: The data acquisition unit is used to acquire control status data; A basic scheme generation unit is used to generate a basic target angle based on the target laser power value and the incident laser power value in the control state data. The basic scheme generation unit is connected to the data acquisition unit. The first calibration unit is used to calibrate the power deviation of the basic target angle based on the real-time output power value in the control state data to obtain the calibrated rotation angle. The first calibration unit is connected to the basic scheme generation unit. The second optimization unit is used to perform temperature drift compensation on the power deviation calibration process based on the winding temperature value in the control state data to obtain the target rotation angle. The second optimization unit is connected to the first calibration unit. The zero-point calibration unit is used to calibrate the origin reference position according to the trigger signal of the zero-point photoelectric switch 15 and the relative position of the sensing sheet, so as to obtain the reference origin position. The zero-point calibration unit is connected to the second optimization unit. The execution drive unit is used to convert the target rotation angle and the reference origin position into pulse control signals, and control the stepper motor 13 according to the pulse control signals, so as to drive the air gap zero-order waveplate 5 to rotate through the power transmission chain. The execution drive unit is connected to the zero-point calibration unit.

[0029] Specifically, the electric control module 17 automatically acquires the target laser power value, incident laser power value, real-time output power value, and winding temperature value in real time through the data acquisition unit, replacing manual reading and recording, eliminating delays and misreadings caused by human operation, improving the real-time performance and automation of power control, and solving the technical problem of low efficiency in manual adjustment. The electric control module 17 also establishes a theoretical attenuation model based on Malus's law through the basic scheme generation unit, directly mapping the target power value to the theoretical rotation angle of the waveplate, realizing the quantitative automatic conversion of power to angle, eliminating the arbitrariness of manual estimation and table lookup calculations, providing a precise benchmark for subsequent closed-loop correction, and solving the technical problem of poor accuracy in manual adjustment. Furthermore, the electric control module 17 uses a first calibration unit to dynamically correct the theoretical rotation angle based on the real-time output power feedback value, constructing a power closed-loop control loop, eliminating power deviations caused by optical component installation errors, light source fluctuations, and mechanical transmission clearances in real time, ensuring that the actual output power is consistent with the target value, and solving the problem of poor accuracy caused by the inability to provide real-time feedback correction in manual adjustment. Furthermore, the second optimization unit quantifies and compensates for the mechanical thermal expansion caused by temperature drift based on the winding temperature value, adaptively correcting the difference in thermal expansion between the transmission shaft 10 and the copper bearing 7 caused by temperature changes, suppressing angle drift during long-term operation, improving the long-term stability of the mechanism in variable temperature environments, and solving the problem of insufficient long-term stability caused by lack of temperature drift compensation; the electric control module 17 also automatically calibrates the origin reference position through the zero-point calibration unit, eliminating the cumulative error of stepper motor 13 step loss and mechanical return gap, ensuring that the angle reference reference is unique and repeatable after each power-on or reset, providing a reliable zero-point reference for the angle accuracy of long-term operation, and solving the problem that manual adjustment is difficult to guarantee repeatability of positioning accuracy; the electric control module 17 also converts the optimized target rotation angle into a high-precision pulse control signal through the execution drive unit, driving the stepper motor 13 to drive the air gap zero-level waveplate 5 to rotate precisely, realizing continuous stepless electric adjustment of laser power, avoiding the low efficiency and operation error of manual rotation of the waveplate, improving the resolution and response speed of power adjustment, and solving the technical problems of low efficiency and poor accuracy of manual adjustment.

[0030] Specifically, the control status data includes the target laser power value, the incident laser power value, the real-time output power value, and the winding temperature value. The target laser power value refers to the target laser output power value set by the wafer trimming process. The data acquisition unit acquires the target laser power value through a host computer software interface, which is an industrial communication interface based on the TCP / IP protocol. The data acquisition unit establishes a Socket connection with the host computer through an Ethernet port and receives process parameter data frames containing the target laser power value Pt sent by the host computer. The incident laser power value refers to the original laser power value output by the laser before reaching the air gap zero-order waveplate 5. The data acquisition unit acquires the incident laser power value through an incident laser power meter. The real-time output power value refers to the actual laser power value after passing through the air gap zero-order waveplate 5 and the polarization beam splitter 4. The data acquisition unit acquires the real-time output power value through an output laser power meter. The winding temperature value refers to the real-time temperature of the stepper motor 13 winding. The data acquisition unit acquires the winding temperature value through an embedded thermistor.

[0031] Specifically, the basic scheme generation unit generates a basic target angle based on the target laser power value and the incident laser power value in the control state data, including: Calculate the target transmittance based on the target laser power value Pt and the incident laser power value Pi. ,set up And based on the target transmittance Tt and Malus's law, the theoretical rotation angle θt is calculated, and set The transmission coefficient K is calculated based on the reduction ratio Rg of the reducer and the step angle θs of the stepper motor, and K = θs / Rg is set. The basic target angle θb is also calculated based on the transmission coefficient K and the theoretical rotation angle θt, and θb = θt / K is set.

[0032] Specifically, Malus's law states that when linearly polarized light passes through the polarizing beam splitter 4, the ratio of the transmitted light intensity to the incident light intensity is equal to the square of the cosine of the polarization direction angle. The reduction ratio of the reducer 12 refers to the ratio of the input shaft speed to the output shaft speed of the reducer 12, which is obtained from the product nameplate of the reducer 12. The step angle of the stepper motor 13 refers to the mechanical angle that the stepper motor 13 rotates for each pulse signal received, which is obtained from the product nameplate of the stepper motor 13 and the driver microstepping setting parameter table.

[0033] Specifically, the first calibration unit performs power deviation calibration on the basic target angle based on the real-time output power value in the control state data to obtain the calibrated rotation angle, including: The power deviation ΔP between the real-time output power value Pr and the target laser power value Pt is calculated, and ΔP = Pr - Pt is set. The power deviation ΔP is compared with the first preset tolerance value RC1 and the second preset tolerance value RC2. The degree of power deviation is judged based on the comparison result, and the power deviation of the basic target angle is corrected based on the judgment result. When RC1≤ΔP≤RC2, the first calibration unit determines that the power deviation level meets the standard and does not perform power deviation calibration on the basic target angle; When ΔP < RC1, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ. When ΔP > RC2, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ.

[0034] Specifically, the first and second preset tolerance values ​​refer to the maximum positive and negative deviation range between the actual output power and the target power that is allowed. RC1 is -0.5mW and RC2 is 0.5mW. The reason is that the tolerance limit of the wafer trimming process for power fluctuations is usually no more than ±1% of the nominal value. Taking 0.5mW can cover most low-power trimming scenarios and take into account control stability. The compliance status of the power deviation refers to the state level determined according to the positional relationship of the power deviation value ΔP relative to the preset tolerance range, including compliance and non-compliance. The power-angle sensitivity coefficient refers to the change in output power caused by the rotation of the air gap zero-order waveplate 5 by a unit angle, denoted as S, and is taken as 0.8mW / °. The reason is that the slope of the power attenuation curve of the air gap zero-order waveplate 5 is approximately linear within the commonly used adjustment range. The value of 0.8mW / ° can ensure the balance between correction accuracy and response speed. The commonly used adjustment range refers to 30° to 60°.

[0035] Specifically, the second optimization unit performs temperature drift compensation on the power deviation correction process based on the winding temperature value in the control state data to obtain the target rotation angle, including: The temperature deviation value ΔT is calculated based on the winding temperature value Tr and the reference temperature Tb, where ΔT = Tr - Tb. The temperature deviation value ΔT is then compared with a preset temperature drift value ΔTth. The significance of the temperature drift impact is judged based on the comparison result, and temperature drift compensation is performed during the power deviation calibration process based on the judgment result. Wherein: When ΔT≤ΔTth, the second optimization unit determines that the degree of influence of the temperature drift is not significant, and does not perform temperature drift compensation in the power deviation correction process; When ΔT > ΔTth, the second optimization unit determines that the influence of the temperature drift is significant and performs temperature drift compensation on the power deviation calibration process: calculate the thermal expansion compensation amount Δθth according to the linear expansion coefficient α, and set Δθth = α × L × ΔT × Wm, where L is the effective length of the transmission shaft 10 and Wm is the mechanical transmission error amplification coefficient. Then, perform temperature drift compensation on the calibrated rotation angle θc according to the thermal expansion compensation amount Δθth to obtain the target rotation angle θm, and set θm = θc + Δθth.

[0036] Specifically, the preset temperature drift value refers to the critical temperature deviation value that triggers the temperature drift compensation mechanism, denoted as ΔTth, and set to 10°C. The reason is that when the temperature change exceeds 10°C, the difference in thermal expansion between the copper bearing 7 and the drive shaft 10 will cause the actual angular deviation of the air gap zero-order waveplate 5 to exceed 0.1°, exceeding the precision requirements for laser power control in the wafer trimming process. The significance of the temperature drift impact refers to the state level determined based on the relationship between the temperature deviation value ΔT and the preset temperature drift value ΔTth, including insignificant and significant. The effective length of the drive shaft 10 refers to the length of the drive shaft 10 between the coupling 11 and the... The axial bearing section length between the active synchronous pulleys 8 is denoted as L and is 120mm. The reason is that this length satisfies the torque transmission stiffness between the reducer 12 and the driven hollow synchronous pulley 6, while also taking into account the installation space limitations of the mechanism on the base 2. The mechanical transmission error amplification factor refers to the amplification factor of the linear displacement caused by the thermal expansion of the transmission shaft 10 after being transmitted through the synchronous belt 9 transmission chain and converted into the angle deviation of the zero-order waveplate 5 in the air gap. It is denoted as Wm and is 1.2. The reason is that the elastic modulus of the synchronous belt 9 under tension and the coupling amplification effect of the small displacement of the tensioning wheel 14 on the angle transmission are taken into account.

[0037] Specifically, the zero-point calibration unit controls the stepper motor to rotate at the origin-finding speed Vh. When the sensor triggers the zero-point photoelectric switch to generate a falling edge signal, the current position is recorded as a temporary origin. The stepper motor is then controlled to rotate in the reverse direction to disengage a distance D. The stepper motor is then controlled to rotate in the forward direction again to approach the zero-point photoelectric switch at a low-speed origin-finding speed Vl. When the zero-point photoelectric switch is triggered again, the current mechanical position is calibrated as the reference origin position P0.

[0038] Specifically, in this embodiment, the origin-finding speed is set to 100pps. The reason is to ensure the origin-finding efficiency while avoiding excessive speed that would cause the sensing element to cross the detection blind zone of the zero-point photoelectric switch 15 and result in missed detection. The disengagement distance is set to 50 pulse equivalents. The reason is to ensure that the sensing element is completely disengaged from the sensing area of ​​the zero-point photoelectric switch 15, eliminating the mechanical inertia overshoot when the stepper motor 13 decelerates and stops, and the influence of the return gap of the synchronous belt 9 on the origin positioning accuracy. The low-speed origin-finding speed is 20pps. The reason is to reduce the running speed of the stepper motor 13 when approaching the origin for the second time, reduce the position overshoot when the sensing element triggers the zero-point photoelectric switch 15, and improve the repeatability positioning accuracy of the reference origin angle P0.

[0039] Specifically, the execution drive unit uses the reference origin position P0 as the origin of the absolute pulse coordinate system. It calculates the target pulse position Pm based on the target rotation angle θm, the microstepping number N of the stepper motor, and the step angle θs, and sets Pm = θm × N / θs. It also calculates the number of pulses Np starting from the origin based on the coordinate difference between the target pulse position Pm and the origin of the absolute pulse coordinate system P0, and sets Np = Pm - P0. Based on the number of pulses, it generates a pulse control signal to control the stepper driver to drive the stepper motor to rotate from the origin of the absolute pulse coordinate system P0 to the target pulse position Pm according to the number of pulses Np. The driven hollow synchronous pulley is driven to rotate through the reducer, the coupling, the transmission shaft, the driving synchronous pulley, and the synchronous belt, thereby driving the air gap zero-order waveplate to rotate to the target angle.

[0040] Specifically, the stepper motor 13's microstepping is achieved by subdividing a single step angle into equal fractions using electronic microstepping technology in the driver, denoted as N, with a value of 1600. This is because a 1 / 8 microstepping drive mode is used to subdivide the standard 1.8° step angle θs into 0.225°, improving angular resolution and operational stability, and reducing the impact of stepper motor 13 vibration on the angular positioning accuracy of the air gap zero-order waveplate 5. The step angle refers to the mechanical angle rotated by the stepper motor for each pulse signal received. Generating the pulse control signal based on the pulse count means that the execution drive unit, through the motion control card, generates a corresponding number of square wave pulse sequences according to the calculated pulse count Np, setting the pulse frequency f to satisfy f ≤ Vm. ax×N / θs, where Vmax is the maximum allowable speed of the stepper motor 13, ensuring that the pulse output frequency does not exceed the mechanical response limit of the stepper motor 13. The control of the stepper motor 13 by the pulse signal means that the generated pulse signal is input to the stepper driver, and the stepper driver drives the stepper motor 13 to rotate according to the pulse signal. Each time a pulse is received, the stepper motor 13 rotates by a subdivision step angle. Through the reducer 12, the coupling 11, the transmission shaft 10, the active synchronous pulley 8, and the synchronous belt 9, the driven hollow synchronous pulley 6 is driven to rotate, which in turn drives the air gap zero-order waveplate 5 to rotate to the relative rotation angle, thereby realizing the electric adjustment of the laser power.

[0041] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An electric power adjustment mechanism for a wafer laser trimming device, characterized in that, include: Base; A base, which is connected to the pedestal; A polarizing beam splitter holder, which is connected to the base; A polarizing beam splitter, which is mounted on the polarizing beam splitter holder; Air gap zero-order waveplate; A driven hollow synchronous belt pulley, with the air gap zero-order waveplate fixed inside its hollow interior; The copper bearing bush is fixed to the two end faces of the driven hollow synchronous pulley, and the copper bearing bush is fixed to the base. Active synchronous pulley; A timing belt, wherein the driving timing pulley is connected to the driven hollow timing pulley via the timing belt; A drive shaft, which is connected to the drive synchronous pulley; A coupling that connects to the drive shaft; A speed reducer, which is connected to the coupling; A stepper motor is connected to the reducer, and the stepper motor, the reducer, the coupling, the drive shaft and the drive synchronous pulley are sequentially connected to form a power transmission chain; The tensioning pulley, which is mounted on the base, tensions the timing belt. A zero-point photoelectric switch is mounted on the base; A heat sink is mounted on the surface of the stepper motor; An electric control module, connected to the stepper motor, the zero-point photoelectric switch, and the laser power meter, is used to acquire control status data, generate a basic target angle based on the control status data, perform power deviation correction on the basic target angle, perform temperature drift compensation during the power deviation correction process, obtain the target rotation angle, and control the stepper motor based on the target rotation angle.

2. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 1, characterized in that, The end of the air gap zero-order waveplate away from the driven hollow synchronous belt pulley is arranged opposite to the polarization beam splitter, and the laser incident direction is set to pass through the air gap zero-order waveplate and the polarization beam splitter in sequence to form an optical attenuation path; The driven hollow synchronous pulley is mounted within the copper bearing bush via a precision bearing to provide low-friction rotational support; the copper bearing bush serves to establish a structural reference; the output shaft of the stepper motor is connected to the input end of the reducer to reduce speed and increase torque; the output end of the reducer is connected to one end of the drive shaft via the coupling to compensate for installation errors and transmit rotational motion; the end of the drive shaft away from the coupling is fixedly connected to the driving synchronous pulley to output driving torque; the driving synchronous pulley, the synchronous belt, and the driven hollow synchronous pulley constitute a reduction gear transmission chain to drive the air... The zero-order waveplate rotates; the sensing plate is fixed on the active synchronous pulley to provide a position trigger mark; the zero-point photoelectric switch cooperates with the sensing plate to detect the origin position and generate a reference signal; the electric control module is connected to the driver signal of the stepper motor to output a pulse control signal, the electric control module is connected to the zero-point photoelectric switch to obtain the origin reference position, and the electric control module is also connected to the laser power meter to collect real-time power feedback data. The power transmission chain drives the zero-order waveplate to rotate to the target angle, thereby realizing the electric adjustment of the laser power.

3. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 1, characterized in that, The copper bearing bush is made of brass, and its coefficient of linear expansion is [missing value]. .

4. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 1, characterized in that, The tension force F applied by the tensioning pulley to the synchronous belt satisfies 20N≤F≤30N, and the thermal resistance Rth of the heat sink satisfies Rth≤2.5K / W.

5. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 1, characterized in that, The electric control module includes: The data acquisition unit is used to acquire control status data; The basic scheme generation unit is used to generate a basic target angle based on the target laser power value and the incident laser power value in the control state data; The first calibration unit is used to perform power deviation calibration on the basic target angle based on the real-time output power value in the control state data, and obtain the calibrated rotation angle. The second optimization unit is used to perform temperature drift compensation on the power deviation correction process based on the winding temperature value in the control state data to obtain the target rotation angle. The zero-point calibration unit is used to calibrate the origin reference position based on the trigger signal of the zero-point photoelectric switch and the relative position of the sensing element, so as to obtain the reference origin position. The execution drive unit is used to convert the target rotation angle and the reference origin position into pulse control signals, and control the stepper motor according to the pulse control signals, so as to drive the air gap zero-order waveplate to rotate through the power transmission chain.

6. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 5, characterized in that, The basic scheme generation unit generates a basic target angle based on the target laser power value and the incident laser power value in the control state data, including: Calculate the target transmittance based on the target laser power value Pt and the incident laser power value Pi. ,set up And based on the target transmittance Tt and Malus's law, the theoretical rotation angle θt is calculated, and set The transmission coefficient K is calculated based on the reduction ratio Rg of the reducer and the step angle θs of the stepper motor, and K = θs / Rg is set. The basic target angle θb is also calculated based on the transmission coefficient K and the theoretical rotation angle θt, and θb = θt / K is set.

7. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 6, characterized in that, The first calibration unit performs power deviation calibration on the basic target angle based on the real-time output power value in the control state data to obtain the calibrated rotation angle, including: The power deviation ΔP between the real-time output power value Pr and the target laser power value Pt is calculated, and ΔP = Pr - Pt is set. The power deviation ΔP is compared with the first preset tolerance value RC1 and the second preset tolerance value RC2. The degree of power deviation is judged based on the comparison result, and the power deviation of the basic target angle is corrected based on the judgment result. When RC1≤ΔP≤RC2, the first calibration unit determines that the power deviation level meets the standard and does not perform power deviation calibration on the basic target angle; When ΔP < RC1, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ. When ΔP > RC2, the first calibration unit determines that the compliance of the power deviation is not up to standard, and performs power deviation calibration on the basic target angle: calculate the angle correction amount Δθ according to the power-angle sensitivity coefficient S, set Δθ = ΔP / S, and calculate the calibrated rotation angle θc according to the angle correction amount Δθ, set θc = θb - Δθ.

8. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 7, characterized in that, The second optimization unit performs temperature drift compensation on the power deviation correction process based on the winding temperature value in the control state data to obtain the target rotation angle, including: The temperature deviation value ΔT is calculated based on the winding temperature value Tr and the reference temperature Tb, where ΔT = Tr - Tb. The temperature deviation value ΔT is then compared with a preset temperature drift value ΔTth. The significance of the temperature drift impact is judged based on the comparison result, and temperature drift compensation is performed during the power deviation calibration process based on the judgment result. Wherein: When ΔT≤ΔTth, the second optimization unit determines that the degree of influence of the temperature drift is not significant, and does not perform temperature drift compensation in the power deviation correction process; When ΔT > ΔTth, the second optimization unit determines that the degree of influence of the temperature drift is significant and performs temperature drift compensation on the power deviation calibration process: calculate the thermal expansion compensation amount Δθth according to the linear expansion coefficient α, and set Δθth = α × L × ΔT × Wm, where L is the effective length of the transmission shaft and Wm is the mechanical transmission error amplification coefficient. Then, perform temperature drift compensation on the calibration rotation angle θc according to the thermal expansion compensation amount Δθth to obtain the target rotation angle θm, and set θm = θc + Δθth.

9. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 8, characterized in that, The zero-point calibration unit controls the stepper motor to rotate at the origin-finding speed Vh. When the sensor triggers the zero-point photoelectric switch to generate a falling edge signal, the current position is recorded as a temporary origin. The stepper motor is then controlled to rotate in the reverse direction to disengage a distance D. The stepper motor is then controlled to rotate in the forward direction again to approach the zero-point photoelectric switch at a low-speed origin-finding speed Vl. When the zero-point photoelectric switch is triggered again, the current mechanical position is calibrated as the reference origin position P0.

10. The electric power adjustment mechanism of the wafer laser trimming equipment according to claim 9, characterized in that, The execution drive unit uses the reference origin position P0 as the origin of the absolute pulse coordinate system. It calculates the target pulse position Pm based on the target rotation angle θm, the microstepping number N of the stepper motor, and the step angle θs, and sets Pm = θm × N / θs. It also calculates the number of pulses Np starting from the origin based on the coordinate difference between the target pulse position Pm and the origin of the absolute pulse coordinate system P0, and sets Np = Pm - P0. Based on the number of pulses, it generates a pulse control signal to control the stepper driver to drive the stepper motor to rotate from the origin of the absolute pulse coordinate system P0 to the target pulse position Pm according to the number of pulses Np. The driven hollow synchronous pulley is driven to rotate through the reducer, the coupling, the transmission shaft, the active synchronous pulley, and the synchronous belt, thereby driving the air gap zero-order waveplate to rotate to the target angle.

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