A high-precision power perturbation suppression and amplitude stabilization control method and system for a rotating fluorescent wheel laser light source

Abstract

The application discloses a high-precision power disturbance suppression and amplitude stabilization control method and system for a rotating fluorescent wheel laser light source. The application proposes a rotating fluorescent wheel laser light power stabilization method and system based on real-time photoelectric detection, spectrum identification and closed-loop compensation control. A multi-point photoelectric detection unit is arranged at a fluorescent exit end to collect output light power signals in real time, spectrum analysis and harmonic tracking are performed in combination with a digital control unit (FPGA / ARM), a periodic disturbance component related to wheel speed is identified, and laser drive input is dynamically adjusted through closed-loop feedback to realize real-time suppression and compensation of power fluctuation. The scheme effectively solves the problem of periodic power fluctuation caused by structural error of the rotating fluorescent wheel, and provides a dynamic and self-adaptive power stabilization control means for high-brightness laser illumination and precise optical measurement systems.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-power and high-precision laser illumination or detection, and particularly relates to a high-precision power disturbance suppression and amplitude stabilization control method and system for a rotating fluorescent wheel laser light source. BACKGROUND

[0002] Rotating fluorescent wheel excitation type laser light sources have been widely used in laser projection, automobile lighting and high-brightness display systems due to their high brightness, high efficiency and compact structure. However, in actual applications, the system output light power still has obvious periodic fluctuations even under constant current driving conditions. The fluctuations are closely related to the rotation speed of the fluorescent wheel and its harmonic frequency, and the main reason is that the fluorescent wheel has structural errors such as radial runout, axial runout, uneven thickness of the fluorescent layer and non-uniformity of the bonding layer when rotating at high speed. These geometric deviations cause the laser focal point to periodically shift on the surface of the fluorescent layer, resulting in changes in local incident energy density and fluorescent emission efficiency, thereby forming periodic light power fluctuations.

[0003] Most of the domestic and foreign researches on rotating fluorescent wheels focus on optical structure and heat dissipation design, and the control of output power fluctuations mainly relies on electrical current stabilization schemes or mechanical structure optimization. For example, a common scheme is to use a constant current driving power supply (such as patent EP0596357A1) (such as a linear current stabilizer or a digital programmable current source) at the end of the laser diode to reduce the influence of power supply noise on power. This type of system only establishes feedback in the electrical link and cannot suppress the optical end fluctuations caused by mechanical structural errors.

[0004] Another type of scheme is to improve the structure or processing precision of the fluorescent wheel. Existing researches usually reduce the runout error by improving the bearing concentricity, controlling the disc thickness tolerance, and improving the bonding process. For example, patents US10036944B2 and US9235045B2. These methods can improve the system consistency at the time of delivery, but they are static compensation methods. When the fluorescent wheel is under high speed and high thermal load conditions, dynamic deformation will still occur due to thermal expansion, material unevenness and centrifugal stress, making it difficult to completely eliminate power fluctuations.

[0005] In addition, some documents also try to add an integrating sphere or a diffuser sheet in the optical path to smooth the output light field (such as patent EP0596357A1). This method can alleviate the brightness flicker to some extent, but at the same time, it brings problems such as light efficiency decline, increased structural complexity and heat accumulation, and cannot suppress periodic disturbances from the source.

[0006] Patents US9509966B2, WO2011123988A1, and US9509966B2 incorporate a phosphor wheel rotation speed detection device in the projection system. By detecting the wheel speed signal, they synchronize the laser modulation phase with the phosphor wheel's angular position, thereby improving color and brightness uniformity. However, these solutions only aim for time synchronization and do not use output light power as a controlled variable for closed-loop feedback control; therefore, they lack effective suppression of periodic fluctuations in light power caused by wheel geometric errors. Patent WO2011123988A1 provides a method for stabilizing emitted light in a color wheel / phosphor wheel system through position synchronization and pre-stored compensation data. It has identified the problem of light intensity fluctuations caused by "uneven wheel distribution / wheel rotation offset," but its solution remains at the "pre-calibration compensation" level. This involves pre-measuring the brightness fluctuation for a full rotation, creating a compensation data table (look-up table), and adjusting the ED drive based on the angle synchronization signal after each rotation. Although patent WO2011123988A1 also involves compensating for light source drive by detecting light intensity, its compensation method is based on position synchronization adjustment of a "pre-stored compensation data table," which is a typical static feedforward method and lacks functions such as real-time error extraction, frequency band decomposition, harmonic identification, and closed-loop feedback control. This document neither solves the power harmonic problem caused by mechanical errors of the fluorescent wheel (radial sway, axial sway, non-uniform thickness, etc.) nor provides a real-time stable power mechanism suitable for laser drive current modulation. Therefore, it cannot achieve the dynamic harmonic suppression and full-band power steady-state control required by this invention.

[0007] In addition, although existing research has developed high-bandwidth FPGA digital servo systems in the field of digital control, which can achieve MHz-level feedback bandwidth (e.g., Yu S.-J. et al., The performance and limitations of FPGA-based digital servos for atomic, molecular, and optical physics experiments, Review of Scientific Instruments, 89(2): 025107, 2018; Pomponio M. et al., FPGA-based Low-Latency Digital Servo for Laser Power and Frequency Control, NIST Technical Report, 2019), these systems are mostly used for laser frequency or amplitude stabilization, and there is no mature application for compensating for periodic intensity fluctuations caused by rotating optical elements (such as fluorescent wheels).

[0008] In summary, existing research techniques mostly focus on constant current stabilization, structural fabrication, or time synchronization, and have not yet established a real-time closed-loop compensation mechanism with output optical power as the feedback object. Currently, there is a lack of a stable power control scheme that can perform real-time detection, spectrum identification, and dynamic compensation for periodic power disturbances caused by mechanical errors of the rotating phosphor wheel. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art by proposing a new system and method that can effectively suppress the aforementioned periodic fluctuations and improve the brightness stability and reliability of high-power laser light sources.

[0010] The technical solution to achieve the purpose of this invention is as follows: On the one hand, a high-precision power disturbance suppression and amplitude stabilization control method for a rotating phosphor wheel laser source is provided. The method suppresses output power fluctuations through spectral sampling, real-time photoelectric detection and closed-loop feedback control, thereby obtaining a stable beam output.

[0011] On the other hand, a control system for implementing the high-precision power disturbance suppression and amplitude stabilization control method is provided, the control system comprising:

[0012] A rotating fluorescent wheel is used to achieve fluorescence conversion and thermal diffusion;

[0013] Drive power supply, used to provide reference DC drive current and modulation current For the laser;

[0014] A laser that outputs single-wavelength or multi-wavelength laser light under the action of the driving power supply, used to excite a rotating phosphor wheel;

[0015] A dichroic mirror has high reflectivity for the laser wavelength output by the laser and is used to couple the laser to the rotating phosphor wheel; at the same time, it has high transmittance for the broadband fluorescence generated by the rotating phosphor wheel and is used to allow the converted broadband fluorescence to be transmitted and enter the spectroscopic sampling module.

[0016] The lens group is used to collimate and focus the broadband fluorescence generated by the rotating fluorescence wheel, which is then transmitted through a dichroic mirror into the beam-splitting module.

[0017] The beam splitting and sampling module is used to split the beam transmitted through the dichroic mirror into a main beam and a sampling beam. The main beam serves as the stable output of the system, while the sampling beam is output to the photoelectric detection module for optical power detection.

[0018] The photoelectric detection module is used to convert the optical signal of the sampling beam into an electrical signal;

[0019] The data acquisition module is used to realize the digital acquisition of electrical signals and obtain the optical power signal of the fluorescent beam;

[0020] The signal processing and control module is used to calculate the modulation current for closed-loop stabilization of the laser output power based on the optical power signal, and output it to the feedback module.

[0021] The feedback module is used to feed back the modulation current output by the signal processing and control module to the drive power supply to achieve dynamic compensation of optical power.

[0022] Furthermore, the photoelectric detection module enables multi-channel detection, including a beam splitter, a four-quadrant photodetector, a transimpedance amplifier, and a filtering unit;

[0023] The beam splitter is used to split the sampling beam so that it is respectively incident on the four detection channels of the four-quadrant photodetector.

[0024] Each detection channel of the four-quadrant photodetector is equipped with a set of transimpedance amplifiers and filtering units. Each transimpedance amplifier is used to convert the photocurrent signal of the corresponding detection channel into a voltage signal, and the filtering unit removes high-frequency noise.

[0025] Furthermore, the data acquisition module includes a multi-channel synchronous ADC module, a normalization preprocessing module, and a fusion module;

[0026] The multi-channel synchronous ADC module is used to synchronously digitize and acquire the photoelectric signals output by the multiple detection channels of the photoelectric detection module.

[0027] The normalization preprocessing module is used to normalize and correct the output of each channel of the multi-channel synchronous ADC module so that the response amplitude is unified to the same reference scale.

[0028] The fusion module is used to perform weighted fusion processing on the normalized results of each channel to obtain the normalized optical power signal of the fluorescence beam.

[0029] Furthermore, the function for the weighted fusion processing is:

[0030]

[0031] in,

[0032]

[0033]

[0034]

[0035] In the formula, This represents the normalized optical power signal. Let represent the normalized photoelectric signal corresponding to the i-th detection channel of the four-quadrant photodetector at time t. The calibration weights for the i-th probe channel are generated based on the initial power-on self-test data. This represents the voltage signal corresponding to the i-th detection channel of the four-quadrant photodetector. These correspond to the four adjacent detection channels of the four-quadrant photodetector, respectively. Represents the spatial jitter norm; Indicates the adaptive penalty coefficient; Indicates within the preset statistical time window Synthesized signal from two diagonal detection channels and The calculated covariance; They represent the same statistical time window. Inside and Standard deviation; The gain calibration parameter / scaling factor represents the adaptive penalty coefficient, used to adjust... The magnitude and sensitivity make It adaptively adjusts according to the changes in the correlation between the two diagonal signals; The combined optical power signals along the two diagonal directions of the four-quadrant detector are respectively:

[0036] .

[0037] Furthermore, the signal processing and control module includes a decomposition unit, a comprehensive control instruction generation unit, and a conversion unit;

[0038] The decomposition unit is used to construct a frequency-domain hierarchical parallel control architecture. This architecture utilizes the principle of spectrum decomposition to split the normalized optical power signal into two independent parallel control channels: a low-frequency voltage regulation channel and a harmonic vector locking channel. The low-frequency voltage regulation channel aims to eliminate non-periodic slow-varying errors caused by laser thermal effects, aging, and circuit temperature drift. The harmonic vector locking channel aims to suppress periodic disturbances at specific frequencies caused by mechanical errors of the phosphor wheel.

[0039] The integrated control instruction generation unit is used to construct an integrated control instruction quantity based on the decomposition results of the decomposition module.

[0040] The conversion unit is used to convert the comprehensive control command quantity into a modulation current. The value is input to the drive power supply.

[0041] Furthermore, the integrated control command quantity is represented as follows: :

[0042]

[0043] In the formula, This represents the low-frequency voltage regulation control quantity output by the low-frequency voltage regulation channel. This represents the harmonic feedback control quantity output by the harmonic vector locking channel;

[0044] The low-frequency voltage regulation channel includes:

[0045] The signal conditioning unit is used to perform low-pass filtering on the normalized optical power signal;

[0046] A PID controller is used to generate low-frequency voltage regulation control quantities based on the low-frequency components after low-pass filtering. , represented as:

[0047]

[0048] In the formula, This represents the proportionality coefficient, used to suppress low-frequency errors. This represents the integral coefficient, used to eliminate steady-state errors and maintain long-term average optical power. These represent differential coefficients, used to improve dynamic response and suppress rapid changes; This represents the optical power signal after low-pass filtering; t represents time t.

[0049] Furthermore, the harmonic vector locking channel allows for simultaneous compensation of multiple orders, and the output harmonic feedback control quantity... Represented as:

[0050] in, The signal is the real-time dynamic compensation signal at time t, and this signal needs to satisfy:

[0051]

[0052] In the formula, , They represent the first The amplitude and phase of the second harmonic; K represents the harmonic order, which can be customized and extended; This indicates the fundamental frequency of the fluorescent wheel rotation.

[0053] Furthermore, the real-time dynamic compensation signal The construction is as follows:

[0054]

[0055]

[0056] in,

[0057]

[0058] In the formula, This represents the harmonic error signal in complex form. Indicates the first The projection component of the first harmonic error signal onto the in-phase orthogonal basis is used to characterize the correlation between the first harmonic and the reference cosine basis function. Indicates the first The projection component of the first harmonic error signal onto the orthogonal basis is used to characterize the correlation between the first harmonic and the reference sinusoidal basis function. This represents the normalized optical power signal. This represents the expected operation within a time averaging or sliding time window, used to average the product of the error signal and the reference basis function within a preset time interval to suppress random noise and extract the stable amplitude and phase information of the corresponding harmonic components.

[0059] On the other hand, a method for detecting the rotational speed of a fluorescent wheel based on the aforementioned control system is provided, the detection method comprising:

[0060] Step 1: Perform a Fast Fourier Transform on the normalized optical power signal to obtain the amplitude spectrum;

[0061] Step 2: Based on the amplitude spectrum, obtain the main harmonic frequency of the optical power signal. ;

[0062] Step 3, based on the main harmonic frequency The rotational speed of the fluorescent wheel was calculated by reverse calculation. The calculation formula is:

[0063]

[0064] in,

[0065]

[0066] In the formula, The order corresponding to the main harmonic.

[0067] Compared with the prior art, the significant advantages of this invention are:

[0068] (1) To address the periodic and quasi-periodic fluctuations in optical power caused by structural errors in the rotating phosphor wheel, this invention constructs a weighted fusion feedback model based on multi-channel photoelectric detection signals and introduces a spatial jitter norm and an adaptive penalty coefficient. This effectively suppresses optical power fluctuations caused by structural errors such as uneven phosphor layer thickness and radial and axial runout of the wheel. Compared with existing technologies based solely on single-point power detection, this invention can dynamically eliminate the influence of structural errors on optical power stability without relying on additional mechanical precision improvements, thereby significantly improving the system's stable power performance under high-speed conditions.

[0069] (2) During the system startup phase, this invention automatically identifies the rotation speed information of the rotating phosphor wheel and the corresponding primary and secondary harmonic frequency components by performing frequency domain analysis or equivalent processing on the normalized optical power signal, and adaptively matches the reference frequency, filtering parameters, and control bandwidth of the harmonic locking channel accordingly. During system operation, the control gain and phase compensation amount of each harmonic compensation channel are adaptively adjusted based on the real-time monitored optical power fluctuation amplitude and phase change, thereby avoiding the control mismatch problem caused by manual tuning or fixed parameter settings in the prior art, and achieving long-term stable power operation.

[0070] (3) This invention introduces a harmonic vector locking control mechanism based on orthogonal demodulation to decompose optical power fluctuations into in-phase and quadrature components in the frequency domain, and simultaneously characterizes the amplitude and phase information of the harmonic components in the form of complex vectors, thereby achieving precise suppression of the target harmonic components. Compared with traditional methods, this invention can maintain a stable and effective harmonic suppression effect even when the phase drifts or the disturbance frequency changes slightly, significantly improving the system's adaptability to dynamic operating conditions.

[0071] (4) By performing weighted fusion and correlation analysis on the signals from multiple photoelectric detection channels, this invention can construct an overall optical power fluctuation model and adaptively adjust the feedback gain and compensation phase according to the phase difference and correlation between different spatial sampling channels, thereby achieving coordinated stable power control in the spatial dimension. This scheme effectively reduces the measurement error introduced by changes in spot shape, optical axis offset, or local non-uniform emission, and improves the representativeness and robustness of the optical power feedback signal, making it particularly suitable for high-brightness laser illumination and high-precision optical measurement scenarios.

[0072] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the control system for a high-precision power disturbance suppression and amplitude stabilization control method in one embodiment. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0075] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0076] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0077] In high-power laser illumination or detection systems, although constant current drive circuits can provide stable current input, significant periodic fluctuations in system output optical power still occur after a rotating phosphor wheel is introduced into the optical path. These fluctuations are closely related to the phosphor wheel's rotational speed and its harmonic frequencies. The primary source is not electrical noise or air turbulence, but rather optical focus shifts and localized luminous efficiency variations caused by mechanical and geometric accuracy errors in the phosphor wheel (including radial and axial sway, non-uniform phosphor layer thickness, and inconsistent adhesive layers). These periodic optical power fluctuations not only cause output brightness flicker and increased signal noise, but also affect the measurement stability and repeatability of high-brightness projection, precision illumination, and optical detection systems.

[0078] Regardless of improvements in the machining precision, dynamic balance, or material uniformity of the fluorescent wheel, slight geometric deviations and thermal deformations are unavoidable under high-speed and high-thermal-load conditions. Because these structural errors vary over time and exhibit periodic repetition, traditional constant-current stabilization or analog power control (APC) methods cannot effectively compensate for them. These methods can only maintain a stable laser injection current but cannot identify and suppress periodic power disturbances caused by wheel surface deformation and beam spot shift.

[0079] To address the aforementioned problems, this invention proposes a method and system for stabilizing the optical power of a rotating phosphor wheel laser based on real-time photoelectric detection, spectrum identification, and closed-loop compensation control. By setting up multiple photoelectric detection units at the phosphor emission end, the output optical power signal is acquired in real time. Combined with a digital control unit (using, but not limited to, FPGA / ARM), spectrum analysis and harmonic tracking are performed to identify periodic disturbance components related to the wheel speed. Through closed-loop feedback, the laser drive input is dynamically adjusted to achieve real-time suppression and compensation of power fluctuations. This scheme effectively solves the problem of periodic optical power fluctuations caused by structural errors in the rotating phosphor wheel, providing a dynamic and adaptive power stabilization control method for high-brightness laser illumination and precision optical measurement systems.

[0080] In one embodiment, a high-precision power disturbance suppression and amplitude stabilization control method for a rotating phosphor wheel laser source is provided. This method suppresses output power fluctuations through spectral sampling, real-time photoelectric detection, and closed-loop feedback control, thereby obtaining a stable beam output. This method is applicable to the detection and feedback control of unstable laser output power caused by mechanical and geometric accuracy errors of the phosphor wheel in high-power, high-precision laser illumination or detection systems.

[0081] Furthermore, in one embodiment, combined with Figure 1 The control system includes:

[0082] A rotating fluorescent wheel is used to achieve fluorescence conversion and thermal diffusion;

[0083] Drive power supply, used to provide reference DC drive current and modulation current For the laser;

[0084] A laser that outputs single-wavelength or multi-wavelength laser light under the action of the driving power supply, used to excite a rotating phosphor wheel;

[0085] A dichroic mirror has high reflectivity for the laser wavelength output by the laser and is used to couple the laser to the rotating phosphor wheel; at the same time, it has high transmittance for the broadband fluorescence generated by the rotating phosphor wheel and is used to allow the converted broadband fluorescence to be transmitted and enter the spectroscopic sampling module.

[0086] The lens group is used to collimate and focus the broadband fluorescence generated by the rotating phosphor wheel, and then transmit it through a dichroic mirror into the beam splitter module (here, the fluorescence beam generated by the rotating phosphor wheel has a large divergence angle, so it needs to be collimated and focused to obtain a beam with higher parallelism and better beam uniformity).

[0087] The beam splitting and sampling module is used to split the beam transmitted through the dichroic mirror into a main beam and a sampling beam. The main beam serves as the stable output of the system, while the sampling beam is output to the photoelectric detection module for optical power detection.

[0088] The photoelectric detection module is used to convert the optical signal of the sampling beam into an electrical signal;

[0089] The data acquisition module is used to realize the digital acquisition of electrical signals and obtain the optical power signal of the fluorescent beam;

[0090] The signal processing and control module (FPGA / ARM) is used to calculate the modulation current for closed-loop stabilization of the laser output power based on the optical power signal and output it to the feedback module.

[0091] The feedback module is used to feed back the modulation current output by the signal processing and control module to the drive power supply to realize dynamic compensation of optical power, thereby smoothing optical power fluctuations and obtaining stable output.

[0092] Here, the present invention effectively separates and rationally guides the pump laser and the emitted fluorescence in the same path through the spectral characteristics of "laser reflection + fluorescence transmission", which not only improves the laser utilization rate but also ensures the purity of the output beam, thus realizing fluorescence excitation.

[0093] Preferably, in some embodiments, the laser is a blue laser that excites a rotating phosphor wheel, and the dichroic mirror is a matching blue dichroic mirror.

[0094] It should be noted that in some other embodiments, the excitation source can be replaced by a laser or semiconductor light-emitting device of any wavelength, and the fluorescence conversion medium can also be replaced by phosphors of different emission bands or multi-band phosphor combinations, for example, but not limited to:

[0095] Combination of blue, violet, or near-ultraviolet lasers with green, red, or multi-color phosphors;

[0096] Combination of multi-wavelength lasers with rotating phosphor wheels or equivalent periodic modulation optical structures;

[0097] Laser source and optical conversion device that is non-rotating but has periodic modulation characteristics.

[0098] In the stable power control system of this invention, the control target is not the light intensity of a single wavelength, but the stability of the system's output optical power in the time domain. Therefore, the dichroic mirror not only performs spectral separation but also provides stable and repeatable optical path conditions for power detection and feedback control. This invention does not limit the specific center wavelength, cutoff band, or tilt angle of the dichroic mirror. Depending on different combinations of excitation light sources and fluorescence conversion media, the dichroic mirror can be configured with different spectral characteristics, for example:

[0099] It exhibits high reflectivity in the excitation light band and high transmittance in the fluorescence emission band.

[0100] It may exhibit high reflectivity in the fluorescence emission band and high transmittance in the excitation light band.

[0101] Under the different light source configurations described above, the output optical power disturbances caused by rotating structures, scanning structures, or periodic motion still exhibit periodic or quasi-periodic changes in the time domain. The spatial sampling, spectrum analysis, rotational speed inversion, predictive feedforward, and hierarchical parallel control methods based on optical power signals proposed in this invention can all be directly applied to the aforementioned light source forms, requiring only the selection of matching optical elements according to the specific spectral range.

[0102] Therefore, it can be seen that the stable power control method and system of the present invention have good adaptability to light source types and are not limited by the excitation wavelength or fluorescence emission band.

[0103] Preferably, in some embodiments, the spectral sampling module employs a cubic beam splitter with a transmittance greater than its reflectance. The beam transmitted through the dichroic mirror and the beam transmitted through the cubic beam splitter are used as the main beam, and the beam reflected by the cubic beam splitter are used as the sampling beam.

[0104] More preferably, in some embodiments, the spectral splitting ratio is designed to be, but not limited to, 90% transmission and 10% reflection.

[0105] Furthermore, in one embodiment, the photoelectric detection module realizes multi-channel detection, including a beam splitter, a four-quadrant photodetector, a transimpedance amplifier, and a filtering unit;

[0106] The beam splitter is used to split the sampling beam so that it is respectively incident on the four detection channels of the four-quadrant photodetector.

[0107] Each detection channel of the four-quadrant photodetector is equipped with a set of transimpedance amplifiers and filtering units (using, but not limited to, filters). Each transimpedance amplifier is used to convert the photocurrent signal of the corresponding detection channel into a voltage signal, and the filtering unit removes high-frequency noise.

[0108] It is important to note that in a rotating phosphor wheel laser source system, the unavoidable radial eccentricity, axial sway, uneven phosphor layer thickness, and thermal deformation during high-speed rotation of the phosphor wheel cause the laser focus to shift periodically or quasi-periodically on the phosphor layer surface. This results in a continuous change in the spatial energy distribution of the emitted fluorescent beam over time. (In high-power laser-fluorescence systems, the sampling spot is not an ideally uniform spot, but rather a "speck pattern" with a granular structure. When the phosphor wheel experiences mechanical sway or the laser undergoes a thermally induced change in refractive index, the spot will experience slight positional jitter on the detector surface.) Under these circumstances, even if the overall output power of the system remains constant, the spatial morphology, position, and brightness distribution of the spot will still change significantly. If only a single-position photodetector is used to monitor the output optical power, the luminous flux received by the photodetector will be significantly affected by local spot drift, speckle structure changes, and spatial brightness non-uniformity. This introduces spurious perturbation components into the detection signal that are unrelated to the true global output power (when speckle particles sweep across the photosensitive surface of the detector, or when the edge of the spot cuts through the detector gap, a false "power jump signal" is generated. This signal is not the actual power fluctuation of the light source, but rather spatial noise introduced by the measurement. If this signal is directly fed back to the laser, it will lead to incorrect current adjustment, which will increase system noise). Therefore, the photodetector module proposed in this invention is not only a simple energy harvester, but also a perturbation-resistant optical power synthesis system based on spatial diversity technology. This system utilizes the spatial resolution capability of a four-quadrant photodetector (4-QD) and, through specific digital signal processing algorithms, eliminates measurement artifacts caused by spot micro-motion, speckle, and local turbulence, delivering a high-fidelity, high signal-to-noise ratio pure optical power feedback signal to the laser controller. By using four independent detection channels, the "optical power fluctuation (global common-mode signal)" and "spatial location noise (local differential-mode signal)" are mathematically separated to reconstruct the true power change.

[0109] Furthermore, in one embodiment, the data acquisition module includes a multi-channel synchronous ADC module, a normalization preprocessing module, and a fusion module;

[0110] The multi-channel synchronous ADC module is used to synchronously digitize and acquire the photoelectric signals output by the multiple detection channels of the photoelectric detection module.

[0111] The normalization preprocessing module is used to normalize and correct the output of each channel of the multi-channel synchronous ADC module so that the response amplitude is unified to the same reference scale.

[0112] The fusion module is used to perform weighted fusion processing on the normalized results of each channel to obtain the normalized optical power signal of the fluorescence beam.

[0113] Preferably, in some embodiments, the function for the weighted fusion process is:

[0114]

[0115] in,

[0116]

[0117]

[0118]

[0119] In the formula, This represents the normalized optical power signal. Let represent the normalized photoelectric signal corresponding to the i-th detection channel of the four-quadrant photodetector at time t. The calibration weights for the i-th probe channel are generated based on the initial power-on self-test data. This represents the voltage signal corresponding to the i-th detection channel of the four-quadrant photodetector. These correspond to the four adjacent detection channels of the four-quadrant photodetector, respectively. Represents the spatial jitter norm; Indicates the adaptive penalty coefficient; Indicates within the preset statistical time window Synthesized signal from two diagonal detection channels and The calculated covariance; They represent the same statistical time window. Inside and Standard deviation; The gain calibration parameter / scaling factor represents the adaptive penalty coefficient, used to adjust... The magnitude and sensitivity make It adaptively adjusts according to the changes in the correlation between the two diagonal signals; The combined optical power signals along the two diagonal directions of the four-quadrant detector are respectively:

[0120] .

[0121] Here, when the four-quadrant signals are highly positively correlated (actual power changes), the correlation term approaches 1. No penalty will be imposed, and the original signal details will be preserved.

[0122] When the signal exhibits negative correlation (position jitter), the correlation term approaches -1. The larger value strongly suppresses the synthesized output at that moment, preventing spurious fluctuations from entering the feedback loop.

[0123] Furthermore, in one embodiment, the signal processing and control module includes a decomposition unit, a comprehensive control instruction generation unit, and a conversion unit;

[0124] The decomposition unit is used to construct a frequency-domain hierarchical parallel control architecture. This architecture utilizes the principle of spectrum decomposition to split the normalized optical power signal into two independent parallel control channels: a low-frequency voltage regulation channel and a harmonic vector locking channel. The low-frequency voltage regulation channel aims to eliminate non-periodic slow-varying errors caused by laser thermal effects, aging, and circuit temperature drift. The harmonic vector locking channel aims to suppress periodic disturbances at specific frequencies caused by mechanical errors of the phosphor wheel (sway, uneven thickness).

[0125] The integrated control instruction generation unit is used to construct an integrated control instruction quantity based on the decomposition results of the decomposition module.

[0126] The conversion unit is used to convert the comprehensive control command quantity into a modulation current. The value is input to the drive power supply.

[0127] Preferably, in some embodiments, the integrated control command quantity is represented as follows: :

[0128]

[0129] In the formula, This represents the low-frequency voltage regulation control quantity output by the low-frequency voltage regulation channel. This represents the harmonic feedback control quantity output by the harmonic vector locking channel.

[0130] Preferably, in some embodiments, the low-frequency voltage regulation channel includes:

[0131] (1) Signal conditioning unit, used to perform low-pass filtering on the normalized optical power signal; this unit filters out all high-frequency fluctuations related to rotation, ensuring that the low-frequency channel does not respond to mechanical vibration and avoids bandwidth competition;

[0132] Preferably, the signal conditioning unit employs, but is not limited to, a digital low-pass filter (LPF), with a cutoff frequency of... Set to 1 / 10 of the fundamental frequency of the fluorescent wheel rotation speed;

[0133] (2) PID controller, used to generate low-frequency voltage regulation control quantity based on the low-frequency components after low-pass filtering. , represented as:

[0134]

[0135] In the formula, This represents the proportionality coefficient, used to suppress low-frequency errors. This represents the integral coefficient, used to eliminate steady-state errors and maintain long-term average optical power. These represent differential coefficients, used to improve dynamic response and suppress rapid changes; This represents the optical power signal after low-pass filtering; t represents time t.

[0136] The PID used in this invention is dedicated to DC and low-frequency components and does not handle harmonic disturbances, so as to avoid mutual interference and make the system more stable.

[0137] It should be noted that this invention employs a digital vector closed-loop technology based on IQ demodulation. The rotation of the fluorescent wheel generates periodic power fluctuations with a frequency of [missing information]. And its higher harmonics (120 Hz, 240 Hz, 360 Hz…). Its error term is:

[0138]

[0139] These harmonics cannot be effectively suppressed by PID, therefore, this invention sets up an independent harmonic compensation module (Lockbox), namely the harmonic vector locking channel.

[0140] Preferably, in some embodiments, the harmonic vector locking channel allows for simultaneous compensation of multiple orders, and the output harmonic feedback control quantity... Represented as:

[0141] in, The signal is the real-time dynamic compensation signal at time t, and this signal needs to satisfy:

[0142]

[0143] In the formula, , They represent the first The amplitude and phase of the second harmonic; K represents the harmonic order, which can be customized and extended; This indicates the fundamental frequency of the fluorescent wheel rotation.

[0144] Preferably, in some embodiments, the real-time dynamic compensation signal The construction is as follows:

[0145]

[0146]

[0147] in,

[0148]

[0149] In the formula, This represents the harmonic error signal in complex form. Indicates the first The projection component of the first harmonic error signal onto the in-phase orthogonal basis is used to characterize the correlation between the first harmonic and the reference cosine basis function. Indicates the first The projection component of the first harmonic error signal onto the orthogonal basis is used to characterize the correlation between the first harmonic and the reference sinusoidal basis function. This represents the normalized optical power signal. This represents the expected operation within a time averaging or sliding time window, used to average the product of the error signal and the reference basis function within a preset time interval to suppress random noise and extract the stable amplitude and phase information of the corresponding harmonic components.

[0150] Preferably, in some embodiments, the conversion unit includes an analog-to-digital converter (DAC) and an amplifier; the DAC integrates control command quantities. This is converted into a corresponding analog control signal, which is then amplified by an amplifier to obtain the final modulated current. This current compensation value can effectively offset the periodic power fluctuations caused by phosphor wheel sway, warping, and non-uniformity of the light-emitting layer in real time, thereby smoothing the output power curve.

[0151] After dynamic adjustment by this closed-loop control system, the fluctuation range of laser output power is significantly reduced: low-frequency drift is suppressed, periodic fluctuations are weakened, and the optical power curve tends to be smoother and stabilized near the reference value. This control system realizes real-time compensation for power disturbances caused by mechanical errors of the rotating phosphor wheel, significantly improving the output stability and reliability of high-power laser sources in high-precision applications such as lighting, projection, and optical detection.

[0152] It should be further noted that several alternative or equivalent implementation methods exist, which can achieve the same or similar power stabilization effect without changing the purpose of the invention, and all are within the protection scope of this invention. These include, but are not limited to:

[0153] In terms of control algorithm implementation, in addition to using FPGA and ARM controllers, high-performance DSPs can be used to implement high-speed sampling, digital filtering, harmonic identification, and control output. Alternatively, high-performance microprocessors can be used. The control strategy can also be changed from phase-locked loop (PLL+Notch) to digital algorithms based on adaptive filtering or model predictive control (MPC) to achieve the same periodic disturbance suppression effect. Lightweight neural networks (such as RNNs or small CNNs) can also be used to automatically learn compensation curves from error signals, replacing the traditional PID+Lockbox combination.

[0154] Regarding photoelectric detection structures, a single-point photoelectric detection method can be adopted: in application scenarios where the spot quality is relatively stable or the speckle structure is not obvious, a single photodetector can be used to replace the multi-point sampling device. By increasing bandwidth and reducing noise, real-time monitoring of output power can be achieved to a certain extent. If the system needs to monitor the focal position, spot drift, or non-uniform brightness distribution simultaneously, a CMOS sensor or PSD can be used to replace the multi-channel PD to extract power change information.

[0155] In one embodiment, an operation method based on the control system is provided, the operation method comprising the following steps:

[0156] S1, the reference DC drive current is provided by the drive power supply. and modulation current For the laser;

[0157] S2, the laser outputs a laser beam under constant current conditions and modulation current;

[0158] S3, the laser beam is incident on the dichroic mirror, reflected by the dichroic mirror, collimated and focused by the lens group, and then coupled to the rotating phosphor wheel;

[0159] S4, the broadband fluorescence generated by the rotating fluorescent wheel is collimated and focused by the lens group, then transmitted through the dichroic mirror and emitted to form a fluorescent beam;

[0160] S5, the fluorescent beam is split into two beams after passing through the spectral sampling module. One beam is the main beam, which is used as the system output for illumination or detection applications. The other beam is the sampling beam, which is emitted to the photoelectric detection module for subsequent optical power monitoring.

[0161] S6, the photoelectric detection module converts the optical signal of the sampling beam into an electrical signal;

[0162] S7, the data acquisition module realizes the digital acquisition of electrical signals to obtain the optical power signal of the fluorescent beam;

[0163] S8, the signal processing and control module calculates the modulation current for closed-loop stabilization of the laser output power based on the optical power signal and outputs it to the feedback module;

[0164] S9, the feedback module feeds the modulation current back to the drive power supply to achieve dynamic compensation of optical power.

[0165] For specific limitations on each step of the operating method, please refer to the limitations on the control system of the high-precision power disturbance suppression and amplitude stabilization control method mentioned above, which will not be repeated here. Each step in the above operating method can be implemented entirely or partially through software, hardware, or a combination thereof.

[0166] In a rotating phosphor wheel laser source system, the actual rotational speed of the phosphor wheel is a key parameter determining the frequency distribution of periodic power perturbations. In existing technologies, the phosphor wheel rotational speed is typically obtained through feedback signals from a motor encoder, Hall sensor, or driver.

[0167] However, the above solutions have the following drawbacks: they require additional mechanical or electrical sensors, increasing system complexity and cost; there is a time delay or asynchrony between the rotation speed measurement signal and the actual optical power disturbance; and they cannot directly reflect the "effective rotation speed actually sensed by the optical end", especially in the presence of slip, load fluctuations, or non-ideal drive conditions.

[0168] In the stable power control problem addressed in this invention, the controlled object is not the motor speed itself, but the periodic modulation effect of optical power caused by the rotation of the phosphor wheel. Therefore, the system based on this invention can directly deduce the actual rotation speed of the phosphor wheel from the optical power signal, which helps to build a more tightly coupled and self-consistent control system.

[0169] In one embodiment, a method for detecting the rotational speed of a fluorescent wheel based on the control system is proposed, the detection method comprising:

[0170] Step 1: Perform a Fast Fourier Transform on the normalized optical power signal to obtain the amplitude spectrum;

[0171] Step 2: Based on the amplitude spectrum, obtain the main harmonic frequency of the optical power signal. (Among them, the non-DC component with the largest amplitude usually corresponds to the main harmonic component caused by the rotational speed of the fluorescent wheel).

[0172] Step 3, based on the main harmonic frequency The rotational speed of the fluorescent wheel was calculated by reverse calculation. (Unit: rpm), the calculation formula is:

[0173]

[0174] in,

[0175]

[0176] In the formula, The order corresponding to the main harmonic is found in most practical systems. .

[0177] This detection method does not rely on any additional mechanical speed sensors; instead, it relies entirely on the optical output signal itself to achieve online estimation of the fluorescent wheel's rotational speed. In this way, the system can directly retrieve the actual rotational speed of the fluorescent wheel online from the optical power signal without requiring any mechanical speed sensors.

[0178] It should be noted that the phosphor wheel rotation speed information obtained through optical power spectrum inversion can be used in several key control processes, including but not limited to:

[0179] (1) Harmonic channel adaptive configuration

[0180] The center frequency of the harmonic extraction and compensation module is dynamically updated to ensure that the IQ demodulation or resonance control always locks onto the true disturbance frequency.

[0181] (2) Time base of the prediction feedforward algorithm

[0182] This provides an accurate basis for period division in the harmonic state prediction model, thereby improving the accuracy of the predicted phase.

[0183] (3) System operating condition monitoring and anomaly detection

[0184] When the inverted speed deviates from the set speed, it can be determined as a sudden load change, slippage, or mechanical abnormality.

[0185] (4) Consistency of all-optical closed-loop control

[0186] This allows speed sensing, power detection, and compensation control to all be based on the same optical observation, avoiding the problem of asynchronous multi-source sensing.

[0187] Compared with existing solutions that rely on mechanical or electrical speed sensors, the speed inversion method based on the main harmonic of the optical power spectrum proposed in this invention has at least the following technical advantages: no additional speed sensor is required, reducing system complexity and cost; the speed sensing and optical power disturbance sources are completely consistent, improving control self-consistency; it can reflect the actual impact of load changes or speed perturbations on optical power in real time; and it provides an accurate and synchronous time reference for predictive feedforward and harmonic compensation algorithms.

[0188] Therefore, this detection method constitutes a self-sensing mechanism for the rotational speed of the fluorescent wheel based on optical power signals. It can be used as an independent innovative module in a stable power control system, or it can be used in conjunction with predictive feedforward and harmonic compensation algorithms.

[0189] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the control method, the operation method, or the detection method.

[0190] For specific limitations on each step of the control method, operation method, or detection method, please refer to the limitations on the control method, operation method, detection method, or control system above, and will not be repeated here.

[0191] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the control method, the operation method, or the detection method.

[0192] For specific limitations on each step of the control method, operation method, or detection method, please refer to the limitations on the control method, operation method, detection method, or control system above, and will not be repeated here.

[0193] In summary, this invention effectively solves the problem of periodic power fluctuations caused by structural errors in the rotating phosphor wheel, providing a dynamic and adaptive stable power control method for high-brightness laser illumination and precision optical measurement systems. The system can automatically identify the phosphor wheel rotation speed and corresponding harmonic frequencies during startup, and automatically match notch filter parameters and control bandwidth. During operation, it can dynamically adjust control parameters based on changes in power fluctuation amplitude, achieving long-term stable power operation. Furthermore, by weighted fusion of signals from multiple photoelectric detection channels, an overall power fluctuation model is obtained; the system can adaptively adjust feedback gain and compensation phase based on the phase difference and correlation of signals from each channel, achieving coordinated power stabilization in the spatial dimension.

[0194] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A high-precision power disturbance suppression and amplitude stabilization control system for a rotating phosphor wheel laser source, characterized in that, The control system includes: A rotating fluorescent wheel is used to achieve fluorescence conversion and thermal diffusion; Drive power supply, used to provide reference DC drive current and modulation current For the laser; A laser that outputs single-wavelength or multi-wavelength laser light under the action of the driving power supply, used to excite a rotating phosphor wheel; A dichroic mirror has high reflectivity for the laser wavelength output by the laser and is used to couple the laser to the rotating phosphor wheel; at the same time, it has high transmittance for the broadband fluorescence generated by the rotating phosphor wheel and is used to allow the converted broadband fluorescence to be transmitted and enter the spectroscopic sampling module. The lens group is used to collimate and focus the broadband fluorescence generated by the rotating fluorescence wheel, which is then transmitted through a dichroic mirror into the beam-splitting module. The beam splitting and sampling module is used to split the beam transmitted through the dichroic mirror into a main beam and a sampling beam. The main beam serves as the stable output of the system, while the sampling beam is output to the photoelectric detection module for optical power detection. The photoelectric detection module is used to convert the optical signal of the sampling beam into an electrical signal; The data acquisition module is used to realize the digital acquisition of electrical signals and obtain the optical power signal of the fluorescent beam; The signal processing and control module is used to calculate the modulation current for closed-loop stabilization of the laser output power based on the optical power signal, and output it to the feedback module. The feedback module is used to feed back the modulation current output by the signal processing and control module to the drive power supply to achieve dynamic compensation of optical power. The data acquisition module includes a multi-channel synchronous ADC module, a normalization preprocessing module, and a fusion module; The multi-channel synchronous ADC module is used to synchronously digitize and acquire the photoelectric signals output by the multiple detection channels of the photoelectric detection module. The normalization preprocessing module is used to normalize and correct the output of each channel of the multi-channel synchronous ADC module so that the response amplitude is unified to the same reference scale. The fusion module is used to perform weighted fusion processing on the normalized results of each channel to obtain the normalized optical power signal of the fluorescent beam. The function for the weighted fusion process is: ； in, ； ； ； In the formula, This represents the normalized optical power signal. Let represent the normalized photoelectric signal corresponding to the i-th detection channel of the four-quadrant photodetector at time t. The calibration weights for the i-th probe channel are generated based on the initial power-on self-test data. This represents the voltage signal corresponding to the i-th detection channel of the four-quadrant photodetector. These correspond to the four adjacent detection channels of the four-quadrant photodetector, respectively. Represents the spatial jitter norm; Indicates the adaptive penalty coefficient; Indicates within the preset statistical time window Synthesized signal from two diagonal detection channels and The calculated covariance; They represent the same statistical time window. Inside and Standard deviation; The gain calibration parameter / scaling factor represents the adaptive penalty coefficient, used to adjust... The magnitude and sensitivity make It adaptively adjusts according to the changes in the correlation between the two diagonal signals; The combined optical power signals along the two diagonal directions of the four-quadrant detector are respectively: 。 2. The control system according to claim 1, characterized in that, The photoelectric detection module enables multi-channel detection and includes a beam splitter, a four-quadrant photodetector, a transimpedance amplifier, and a filtering unit. The beam splitter is used to split the sampling beam so that it is respectively incident on the four detection channels of the four-quadrant photodetector. Each detection channel of the four-quadrant photodetector is equipped with a set of transimpedance amplifiers and filtering units. Each transimpedance amplifier is used to convert the photocurrent signal of the corresponding detection channel into a voltage signal, and the filtering unit removes high-frequency noise.

3. The control system according to claim 1, characterized in that, The signal processing and control module includes a decomposition unit, a comprehensive control instruction generation unit, and a conversion unit; The decomposition unit is used to construct a frequency-domain hierarchical parallel control architecture. This architecture utilizes the principle of spectrum decomposition to split the normalized optical power signal into two independent parallel control channels: a low-frequency voltage regulation channel and a harmonic vector locking channel. The low-frequency voltage regulation channel aims to eliminate non-periodic slow-varying errors caused by laser thermal effects, aging, and circuit temperature drift. The harmonic vector locking channel aims to suppress periodic disturbances at specific frequencies caused by mechanical errors of the phosphor wheel. The integrated control instruction generation unit is used to construct an integrated control instruction quantity based on the decomposition results of the decomposition module. The conversion unit is used to convert the comprehensive control command quantity into a modulation current. The value is input to the drive power supply.

4. The control system according to claim 3, characterized in that, The integrated control command quantity is expressed as: : ； In the formula, This represents the low-frequency voltage regulation control quantity output by the low-frequency voltage regulation channel. This represents the harmonic feedback control quantity output by the harmonic vector locking channel; The low-frequency voltage regulation channel includes: The signal conditioning unit is used to perform low-pass filtering on the normalized optical power signal; A PID controller is used to generate low-frequency voltage regulation control quantities based on the low-frequency components after low-pass filtering. , represented as: ； In the formula, This represents the proportionality coefficient, used to suppress low-frequency errors. This represents the integral coefficient, used to eliminate steady-state errors and maintain long-term average optical power. These represent differential coefficients, used to improve dynamic response and suppress rapid changes; This represents the optical power signal after low-pass filtering; t represents time t.

5. The control system according to claim 4, characterized in that, The harmonic vector locking channel allows for simultaneous compensation of multiple orders, and the output harmonic feedback control quantity... Represented as: ； in, The signal is the real-time dynamic compensation signal at time t, and this signal needs to satisfy: ； In the formula, , They represent the first The amplitude and phase of the second harmonic; K represents the harmonic order, which can be customized and extended; This indicates the fundamental frequency of the fluorescent wheel rotation.

6. The control system according to claim 5, characterized in that, The real-time dynamic compensation signal The construction is as follows: ； ； in, ； In the formula, This represents the harmonic error signal in complex form. Indicates the first The projection component of the first harmonic error signal onto the in-phase orthogonal basis is used to characterize the correlation between the first harmonic and the reference cosine basis function. Indicates the first The projection component of the first harmonic error signal onto the orthogonal basis is used to characterize the correlation between the first harmonic and the reference sinusoidal basis function. This represents the normalized optical power signal. This represents the expected operation within a time averaging or sliding time window, used to average the product of the error signal and the reference basis function within a preset time interval to suppress random noise and extract the stable amplitude and phase information of the corresponding harmonic components.

7. A high-precision power disturbance suppression and amplitude stabilization control method based on the control system according to any one of claims 1 to 6, characterized in that, The method suppresses output power fluctuations through spectral sampling, real-time photoelectric detection, and closed-loop feedback control, thereby obtaining a stable beam output.

8. A method for detecting the rotational speed of a fluorescent wheel based on the control system described in any one of claims 1 to 6, characterized in that, The detection method includes: Step 1: Perform a Fast Fourier Transform on the normalized optical power signal to obtain the amplitude spectrum; Step 2: Based on the amplitude spectrum, obtain the main harmonic frequency of the optical power signal. ; Step 3, based on the main harmonic frequency The rotational speed of the fluorescent wheel was calculated by reverse calculation. The calculation formula is: ； in, ； In the formula, The order corresponding to the main harmonic.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the control method as described in claim 7 or the detection method as described in claim 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the control method as described in claim 7 or the detection method as described in claim 8.

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