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CN-121546426-B - High-precision power disturbance suppression and amplitude stabilization control method and system for rotating fluorescent wheel laser light source

CN121546426BCN 121546426 BCN121546426 BCN 121546426BCN-121546426-B

Abstract

The invention discloses a high-precision power disturbance rejection and amplitude stabilization control method and system for a rotating fluorescent wheel laser light source. The invention provides a method and a system for stabilizing laser light power of a rotary fluorescent wheel based on real-time photoelectric detection, spectrum identification and closed-loop compensation control. The multi-point photoelectric detection unit is arranged at the fluorescence emission end, output optical power signals are collected in real time, spectrum analysis and harmonic tracking are carried out by combining a digital control unit (FPGA/ARM), periodic disturbance components related to wheel speed are identified, laser driving input is dynamically regulated through closed loop feedback, and real-time suppression and compensation of power fluctuation are realized. The scheme effectively solves the problem of periodic fluctuation of the optical power caused by structural errors of the rotary fluorescent wheel, and provides a dynamic and self-adaptive stable power control means for a high-brightness laser illumination and precise optical measurement system.

Inventors

  • CAO CHENG
  • JIN ZHILIANG
  • PENG GE
  • XIONG DAXI

Assignees

  • 中国科学院苏州生物医学工程技术研究所

Dates

Publication Date
20260512
Application Date
20260122

Claims (10)

  1. 1. A high precision power disturbance rejection and amplitude stabilization control system for a rotating fluorescent wheel laser light source, the control system comprising: The rotating fluorescent wheel is used for realizing fluorescence conversion and thermal diffusion; A driving power supply for providing a reference DC driving current And modulating the current Supplying a laser; The laser outputs single-wavelength or multi-wavelength laser under the action of the driving power supply and is used for exciting the rotary fluorescent wheel; The dichroic mirror has high reflectivity to the laser wavelength output by the laser and is used for coupling laser to the rotary fluorescent wheel, and meanwhile, the broadband fluorescence generated by the rotary fluorescent wheel has high transmissivity and is used for enabling the converted broadband fluorescence to enter the light splitting sampling module after being transmitted; The lens group is used for collimating and focusing broadband fluorescence generated by the rotary fluorescent wheel and then transmitting the broadband fluorescence into the light splitting module through the dichroic mirror; the beam splitting sampling module is used for splitting the beam transmitted by the dichroic mirror into a main beam and a sampling beam, wherein the main beam is used as the stable output of the system, and the sampling beam is output to the photoelectric detection module and used for detecting the optical power; the photoelectric detection module is used for converting the optical signal of the sampling beam into an electric signal; the data acquisition module is used for realizing digital acquisition of the electric signals and acquiring optical power signals of the fluorescent light beams; The signal processing and control module is used for calculating the modulation current for realizing the closed-loop stable control of the output power of the laser according to the optical power signal and outputting the modulation current to the feedback module; the feedback module is used for feeding back the modulation current output by the signal processing and control module to the driving power supply to realize dynamic compensation of the optical power; The data acquisition module comprises a multichannel synchronous ADC module, a normalization preprocessing module and a fusion module; the multichannel synchronous ADC module is used for synchronously and digitally collecting photoelectric signals output by a plurality of detection channels of the photoelectric detection module; The normalization preprocessing module is used for carrying out normalization correction on the output of each channel of the multichannel synchronous ADC module so as to unify the response amplitude to the same reference scale; The fusion module is used for carrying out weighted fusion processing on the normalized result of each channel to obtain a light power signal normalized by the fluorescent light beam; the function of the weighted fusion process is as follows: ; Wherein, the ; ; ; In the formula, Representing the normalized optical power signal and, Representing normalized photoelectric signals corresponding to the ith detection channel of the four-quadrant photoelectric detector at the moment t, For the calibration weights of the ith probe channel generated based on the initial power-up self-test data, Representing the voltage signal corresponding to the ith detection channel of the four-quadrant photodetector, Four detection channels which are adjacent in sequence and respectively correspond to the four-quadrant photoelectric detectors; representing a spatial dithering norm; Representing an adaptive penalty coefficient; is shown in a preset statistical time window Composite signal of two opposite angle detection channels And (3) with Calculating the covariance; Respectively expressed in the same statistical time window Inner part And (3) with Standard deviation of (2); Gain calibration parameters/scaling coefficients representing adaptive penalty coefficients for tuning The magnitude and sensitivity of (2) are such that Adaptively adjusting according to the correlation change of the two diagonal signals; the synthesized optical power signals respectively representing two diagonal directions of the four-quadrant detector are respectively: 。
  2. 2. the control system of claim 1, wherein the photo-detection module implements multi-channel detection, comprising a beam splitter, a four-quadrant photo-detector, a transimpedance amplifier, and a filtering unit; The beam splitter is used for splitting the sampling beam to be respectively incident to four detection channels of the four-quadrant photoelectric detector; each detection channel of the four-quadrant photoelectric detector is respectively provided with a group of transimpedance amplifiers and a filtering unit, and each transimpedance amplifier is used for converting a photocurrent signal of the corresponding detection channel into a voltage signal and removing high-frequency noise through the filtering unit.
  3. 3. The control system according to claim 1, wherein the signal processing and control module includes a decomposition unit, a comprehensive control instruction generation unit, and a conversion unit; The system comprises a decomposition unit, a frequency domain hierarchical parallel control architecture, a low-frequency voltage stabilizing channel, a harmonic vector locking channel and a control unit, wherein the decomposition unit is used for constructing a frequency domain hierarchical parallel control architecture, and the frequency domain hierarchical parallel control architecture utilizes a frequency spectrum decomposition principle to split a normalized optical power signal into two independent parallel control channels, namely the low-frequency voltage stabilizing channel and the harmonic vector locking channel, wherein the low-frequency voltage stabilizing channel is used for eliminating aperiodic slow-varying errors caused by laser thermal effects, ageing and circuit temperature drift; the comprehensive control instruction generation unit is used for constructing a comprehensive control instruction amount based on the decomposition result of the decomposition module; The conversion unit is used for converting the comprehensive control instruction quantity into a modulation current Value, and input to the driving power supply.
  4. 4. A control system according to claim 3, wherein the integrated control command quantity is expressed as : ; In the formula, Representing the low-frequency voltage stabilizing control quantity output by the low-frequency voltage stabilizing channel, Representing harmonic feedback control quantity output by a harmonic vector locking channel; wherein, the low frequency steady voltage passageway includes: the signal conditioning unit is used for performing low-pass filtering processing on the normalized optical power signal; PID controller for generating low-frequency voltage stabilizing control quantity according to low-frequency component after low-pass filtering Expressed as: ; In the formula, Represents a scaling factor for suppressing the scaling effect of low frequency errors, Represents an integral coefficient for eliminating steady state error, maintaining long-term average light power, Representing differential coefficients for enhancing dynamic response and suppressing rapid changes; the optical power signal after low-pass filtering is represented, and t represents the time t.
  5. 5. The control system of claim 4, wherein the harmonic vector lock-in channel allows multiple orders to be simultaneously compensated, and the harmonic feedback control amount is outputted Expressed as: ; Wherein, the For a real-time dynamic compensation signal at time t, the signal needs to satisfy: ; In the formula, 、 Respectively represent the first K represents harmonic frequency and can be expanded in a self-defined way; indicating the fundamental frequency of rotation of the fluorescent wheel.
  6. 6. The control system of claim 5, wherein the real-time dynamic compensation signal The structure is as follows: ; ; Wherein, the ; In the formula, Representing the harmonic error signal in complex form, Represent the first The projection component of the order harmonic error signal on the in-phase quadrature basis is used for representing the correlation degree of the order harmonic and the reference cosine basis function, Represent the first The projected component of the order harmonic error signal on the quadrature basis, is used to characterize the degree of correlation of the order harmonic with the reference sinusoidal basis function, Representing the normalized optical power signal and, And representing a desired operation in a time average or sliding time window, and performing average processing on the product of the error signal and the reference basis function in a preset time interval to suppress random noise and extract stable amplitude and phase information of the corresponding harmonic component.
  7. 7. The 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 fluctuation through spectroscopic sampling, real-time photoelectric detection and closed-loop feedback control, thereby obtaining stable light beam output.
  8. 8. A method for detecting a rotation speed of a fluorescent wheel based on a control system according to any one of claims 1 to 6, characterized in that the detection method comprises: Step 1, performing fast Fourier transform on a normalized optical power signal to obtain an amplitude spectrum; step 2, based on the amplitude spectrum, obtaining the main harmonic frequency of the optical power signal ; Step 3, based on the main harmonic frequency Reverse-pushing calculation of rotating speed of fluorescent wheel The calculation formula is as follows: ; Wherein, the ; In the formula, The order corresponding to the main harmonic.
  9. 9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the control method according to claim 7 or the detection method according to claim 8 when executing the computer program.
  10. 10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the control method according to claim 7 or the detection method according to claim 8.

Description

High-precision power disturbance suppression and amplitude stabilization control method and system for rotating fluorescent wheel laser light source Technical Field The invention belongs to the technical field of high-power 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 The rotary fluorescent wheel excitation type laser light source has been widely used in laser projection, automobile illumination and high brightness display systems due to its high brightness, high efficiency and compact structure. However, in practical applications, even under constant current driving conditions, significant periodic fluctuations in the system output optical power may still occur. The fluctuation is closely related to the rotating speed of the fluorescent wheel and the harmonic frequency thereof, and the main reasons are that the fluorescent wheel has structural errors such as radial runout, axial runout, uneven thickness of a fluorescent layer, non-uniformity of an adhesive layer and the like when rotating at a high speed. These geometrical deviations cause the laser focus to shift periodically at the surface of the phosphor layer, resulting in a local incident energy density and a change in the fluorescence emission efficiency, thus forming periodic optical power fluctuations. Research on rotating fluorescent wheels at home and abroad is focused on optical structures and heat dissipation designs, and control on output power fluctuation mainly depends on an electrical steady flow scheme or mechanical structure optimization. For example, a common scheme is to use a constant current driving power supply (such as patent EP0596357 A1) at the end of the laser diode (such as a linear current stabilizing or a digital programmable current source) to reduce the influence of power noise on the power, and such a system only establishes feedback in an electrical link, but cannot restrain the fluctuation of the optical end caused by mechanical structure errors. Another class of solutions consists in improving the structural or machining precision of the fluorescent wheel. Existing studies generally reduce runout errors by increasing bearing concentricity, controlling disc thickness tolerances, improving bonding processes, and the like. For example, patent US10036944B2 and patent US9235045B2 can promote system consistency when leaving the factory, but belongs to static compensation means, and when the fluorescent wheel is under the conditions of high rotating speed and high thermal load, dynamic deformation can be caused by thermal expansion, uneven materials and centrifugal stress, so that power fluctuation is difficult to thoroughly eliminate. In addition, some documents have attempted to incorporate an integrating sphere or diffuser in the optical path for smoothing the output light field (as in patent EP0596357 A1). The method can alleviate brightness flicker to a certain extent, but simultaneously brings problems of light effect reduction, structural complexity improvement, heat accumulation and the like, and cannot inhibit periodic disturbance from the source. The patent US9509966B2 and the patent WO2011123988A1 and the patent US9509966B2 are provided with a fluorescent wheel rotating speed detection device in the projection system, and the synchronization of the laser modulation phase and the fluorescent wheel angular position is realized by detecting the wheel speed signal so as to improve the color and brightness uniformity. However, the control targets of the technical schemes are only time synchronization, and the output optical power is not used as a controlled variable to carry out closed loop feedback control, so that the optical power periodic fluctuation caused by the geometric error of the wheel sheet is not effectively inhibited. Patent WO2011123988A1 provides a method for realizing the stability of emergent light in a color wheel/fluorescent wheel system by means of position synchronization and pre-stored compensation data, which has been identified that "uneven distribution of wheel pieces/rotation deviation" causes the problem of fluctuation of light intensity, but the scheme is remained at the "pre-calibrated compensation" level, i.e. the fluctuation of brightness of a whole circle is measured in advance, so as to form a compensation data table (look-up table), and the ED drive is regulated by looking up a table according to an angle synchronization signal every round of rotation of a piece. Although patent WO2011123988A1 also relates to compensating the light source drive by detecting the light intensity, the compensation mode is based on the position synchronous adjustment of a pre-stored compensation data table, belongs to a typical static feedforward mode, and does not have the functions of real-time error extraction, f