Optical phase control method and system for an interferometric system

Abstract

The application discloses an optical phase control method and system of an interference system, and relates to the technical field of optical phase, and solves the problems of poor control timeliness, large error and difficulty in considering convergence speed and steady-state jitter of the existing optical phase control technology. The application discloses an optical phase control method, which initializes a control quantity and a control parameter according to a target reference value of an optical phase; initializes a disturbance frequency, a block correlation quantity; inputs a driving voltage to a phase actuator, and collects a detection voltage signal; updates an error quantity, a cost quantity and the disturbance amplitude; judges whether the control parameter is a current control parameter according to the error quantity; updates the control quantity, and completes the control of the optical phase u n . The application discloses an optical phase control system, which comprises a microcontroller MCU, a DAC digital-analog conversion module, a phase actuator, an optical detection module and an ADC analog-digital conversion module. The application is suitable for the fields of phase stabilization such as fiber interferometer, phase modulation / compensation and coherent detection.

Description

Technical Field

[0001] This invention relates to the field of optical phase technology, and also to the field of optical phase control and interferometry. Background Technology

[0002] In the field of fiber optic interferometric measurement and phase-locking, there is a contradiction between "large-range dynamic tracking" and "low-noise maintenance." On the one hand, the sensing fiber is extremely sensitive to the environment; even slight environmental changes can cause significant phase drift. This requires the control algorithm to have a fast control convergence speed and a large correction range to prevent loss of lock. On the other hand, the refractive index fluctuations caused by atmospheric turbulence are often extremely weak, requiring the system to maintain extremely low background noise in the locked state to avoid drowning out the turbulent signal being measured. PID algorithms based on linear error models are difficult to adapt to the cosine nonlinear response unique to fiber optic interferometers. When the operating point drifts to the peak or trough of the interference curve (sensitivity dead zone), the error signal gain decreases sharply or even reverses phase, causing the PID controller to easily saturate or fail completely.

[0003] Model-free optimization based on random perturbation (SPSA / SPGD) has been widely used in noise-dominated scenarios such as adaptive optics. By superimposing ±1 random perturbations on the control variable and estimating the performance index using a "gradient proxy" with a small number of measurements, iterative optimization can be achieved on unknown or difficult-to-model systems. Although various improvements have been proposed in the literature (such as decoupled SPGD, hierarchical / parallel variants), such as Chinese Patent Publication No. "CN120430370A", entitled "A Multi-Strategy Segmented Fusion Adaptive SPGD Method for Laser Correlated Synthesis Systems", the core idea is to use FPGA to employ symmetrical perturbation, measure the performance evaluation function twice, and use the difference method to find the convergence direction. The perturbation amplitude is fixedly increased or decreased based on the convergence result to achieve the convergence effect, which effectively improves the convergence speed of the algorithm.

[0004] However, phase changes are random, and fixed perturbations cannot effectively detect phase changes. When faced with large phase differences, there is a lack of timely correction methods. Furthermore, existing multi-focus high-throughput platforms (FPGA / PC / high-speed DAC / ADC) lack a systematic approach to key engineering details such as "strictly aligning perturbation-sampling-update with timer / DMA clock cycles on resource-constrained MCUs, dynamically perturbing error trends, using windowed measurements to eliminate transients, and suppressing direction determination deviations under low SNR through block correlation." This makes it difficult to achieve a balance between convergence speed and steady-state jitter in miniaturized coherent / interferometric phase-locked applications.

[0005] In summary, existing optical phase control technologies suffer from poor control timeliness, large errors, and difficulty in balancing convergence speed and steady-state jitter. Summary of the Invention

[0006] This invention alleviates the problems of poor control timeliness, large errors, and difficulty in balancing convergence speed and steady-state jitter in existing optical phase control techniques. This invention provides the following solution:

[0007] Option 1: An optical phase control method for an interferometric system, comprising the following steps:

[0008] Step S01, based on the target reference value of the optical phase V ref Initialize control variables u n and control parameters;

[0009] The control parameters include coarse control parameters and fine control parameters;

[0010] The coarse control parameters include the disturbance amplitude. d k and block length M The fine control parameters include the disturbance amplitude. d' and block length M’ ;

[0011] Step S02, Initialize the number of perturbations m =0, block correlation quantity S =0;

[0012] Step S03: Input a driving voltage to the phase actuator, acquire several detection voltage signals, and obtain a sampling sequence; based on the target reference value... V ref Update the error amount using the obtained sampling sequence. e k Cost and the amplitude of the disturbance d k ;

[0013] The driving voltage pass

[0014]

[0015] Obtain, among which, ;

[0016] Step S04, based on the current error amount e k Select control parameters.

[0017] like If so, then the fine control parameter is selected as the selection control parameter;

[0018] like If so, then the coarse control parameter is selected as the selection control parameter;

[0019] in, T1 For fine error threshold, T2 This is a coarse error threshold. T1 < T2 ;

[0020] If the current control parameter is different from the selected control parameter, the current control parameter is replaced with the selected control parameter, and then step S02 is executed;

[0021] Otherwise, the number of perturbations is performed. m++ Block-related quantities Return to step S03 until... m M Proceed to step S05;

[0022] Step S05, if in the preceding consecutive M In the next iteration, the error amount e k If the error remains below the threshold and the control parameters remain fine, then the control of the optical phase is complete.

[0023] Otherwise, based on the current error amount e k Block correlation quantity Block length M and the amplitude of the disturbance d k For the control quantity u n Perform the update, return to step S02, and perform the next update.

[0024] Furthermore, in one embodiment of the present invention, in step S03, by...

[0025]

[0026] Update error e k ,in, P k For voltage measurement;

[0027] voltage measurement P k pass

[0028]

[0029] Obtain, among which, The instantaneous voltage value read by the ADC; The first part of the sampling sequence There are 10 detected voltage signals, and the sampling sequence contains a total of 100 signals. One detection voltage signal.

[0030] Furthermore, in one embodiment of the present invention, in step S03, by...

[0031]

[0032] Update cost ,in, P k For voltage measurement.

[0033] Furthermore, in one embodiment of the present invention, in step S03, by...

[0034]

[0035] Update the disturbance amplitude, where, d min This is the lower limit of the disturbance amplitude. d max This is the upper limit of the disturbance amplitude. or The damping factor for the perturbation amplitude update law. S k Let be the phase-sensitive surrogate quantity, and sign() be the sign function.

[0036] Furthermore, in one embodiment of the present invention, in step S05, based on the error amount... e k Block correlation quantity S Block length M and the amplitude of the disturbance d k Obtain gradient and the smoothing error amount Based on the gradient and the smoothing error amount For the control quantity u n Adaptive step size, amplitude limiting, range projection, and smooth speed limiting are implemented to achieve updates;

[0037] The gradient pass

[0038]

[0039] get;

[0040] The smoothing error pass

[0041]

[0042] We obtain , where β is the smoothing coefficient.

[0043] Option 2: An optical phase control system for an interferometric system, the control system comprising a microcontroller (MCU), a digital-to-analog converter (DAC), a phase actuator, an optical detection module, and an analog-to-digital converter (ADC);

[0044] The microcontroller (MCU) has an embedded computer program that executes the optical phase control method described in Scheme 1 during runtime, and is used to convert the driving voltage obtained by the control method into a driving voltage. Send to the DAC (Digital-to-Analog Converter) module;

[0045] The DAC digital-to-analog converter module is used to convert the driving voltage The signal is converted into an analog signal and sent to the phase actuator.

[0046] The phase actuator is used to interfere with the optical path;

[0047] The optical detection module is used to detect the optical signal of the optical path and convert it into a detection voltage signal; it is also used to send the detection voltage signal to the ADC analog-to-digital converter module.

[0048] The ADC analog-to-digital converter module is used to convert the detected voltage signal into a digital signal; it is also used to send the digital signal to the microcontroller MCU as a detected voltage signal.

[0049] Furthermore, in one embodiment of the present invention, the microcontroller MCU further includes a timer TIM_DAC, which is used to control the DAC digital-to-analog conversion module to perform digital-to-analog conversion according to a predetermined cycle.

[0050] Furthermore, in one embodiment of the present invention, the microcontroller MCU further includes a timer TIM_ADC, which is used to control the ADC analog-to-digital conversion module to perform analog-to-digital conversion according to a predetermined sampling cycle.

[0051] Furthermore, in one embodiment of the present invention, the microcontroller MCU further includes a DMA control / interrupt module, which is used to write the sampling sequence into a buffer through double buffering; and is also used to generate an interrupt signal to start a buffer read operation when the buffer is half full.

[0052] The optical phase control method and system for an interferometric system described in this invention is a closed-loop control method based on hysteresis dual-mode adaptive perturbation. This method effectively alleviates the shortcomings of existing optical phase control techniques, such as poor control timeliness, large errors, and difficulty in balancing convergence speed and steady-state jitter. Specific beneficial effects include:

[0053] 1. The optical phase control method described in this invention differs from traditional adaptive control methods that employ fixed perturbation amplitudes or structured perturbations (such as symbol sequences or orthogonal sequences). This invention is based on a self-evolutionary mechanism for the perturbation amplitude according to the error trend. This mechanism updates the error amount... e k Phase sensitivity proxy S k The coupling determines whether the phase response improves or deteriorates, thereby dynamically enhancing or suppressing the perturbation amplitude δ. k This gives the perturbation inherent directional memory and dynamic evolution capabilities. Due to the difference in error before and after the update... e k It directly reflects the true effect of the previous perturbation on the optical phase, thus realizing a perturbation update law that is strongly coupled with the physical changes in phase. As a result, it can still maintain a higher direction determination accuracy under noise, drift and optical path perturbation, and is particularly suitable for practical phase control systems with low update bandwidth and nonlinear response.

[0054] 2. The optical phase control method described in this invention is a dual-mode control structure with hysteresis characteristics. It utilizes two threshold values ​​(...) T 1 and T 2) The system manages the switching between coarse and fine control parameters. Coarse control parameters have larger perturbations and a smaller m-block length, suitable for rapid homing with large deviations. Fine control parameters maintain smaller perturbations and a larger m-block length, used for noise reduction and stability maintenance near the target. The hysteresis during the switching between coarse and fine control parameters avoids frequent mode jumps in the critical region, significantly reducing mode flutter and enabling better performance in both the "rapid entry—smooth maintenance" phases. This structure naturally matches the trend perturbation mechanism: coarse control parameter updates dominate rapid approximation, while fine control parameter updates and the rate limiting mechanism jointly suppress jitter, thus forming a two-stage adaptive behavior flow.

[0055] 3. The optical phase control method described in this invention further introduces a triple constraint link consisting of adaptive step size, single-step limiting, boundary projection, and smooth speed limiting during the updating of coarse and fine-mode control parameters. This is used to suppress overshoot, oscillation, and large jumps caused by instantaneous error fluctuations. In traditional control methods, the dynamic step size is difficult to match with the nonlinear phase response, and the limiting strategy cannot adjust the intensity according to the error trend. This invention combines the design of "trend disturbance - dual-mode hysteresis - triple constraint" to form a synergistic vibration suppression effect against error dynamics: the trend provides direction and intensity determination, the dual-mode provides phased behavior management, and the triple constraint provides fine-grained output control. Although limiting and projection are common techniques, in this invention, after being combined with the trend disturbance and hysteresis structure, the overall stability is significantly improved, producing a vibration suppression effect far exceeding the sum of the three individual effects.

[0056] 4. The optical phase control method described in the present invention automatically obtains the target reference value Vref through the above-mentioned self-evolving mechanism of perturbation amplitude based on error trend, the dual-mode control structure with hysteresis characteristics, and the triple-constraint link. Subsequently, during the operation process, symbol perturbation injection, synchronous acquisition, window measurement, block correlation estimation, adaptive update, and dual-mode switching with hysteresis characteristics are sequentially executed, so as to maintain the optical phase stable near the target reference value Vref on a resource-constrained microcontroller platform. Without relying on high computing power and complex phase-locked structures, it can achieve strong coupling with embedded timing, and still achieve both fast convergence of large deviations and low jitter steady state of small deviations under low computing power conditions, and suppress misoperations caused by output / sampling asynchronization and low signal-to-noise ratio in measurement.

[0057] 5. The optical phase control system described in the present invention is an optical phase closed-loop control system that matches the optical phase control method of the present invention. The control system includes a microcontroller MCU, a DAC digital-to-analog conversion module, a phase actuator, an optical detection module, and an ADC analog-to-digital conversion module. The microcontroller MCU internally has a control algorithm module, a timer TIM_DAC, a timer TIM_ADC, and a DMA control / interrupt. Utilize the half-buffered characteristics of DAC / ADC / DMA in the embedded platform to construct a real-time perturbation-sampling-trend-update closed loop, and make full use of the streaming sampling rhythm to avoid interrupt jitter, so that the perturbation action, sampling moment, and trend calculation maintain a fixed time relationship.

[0058] This mechanism enables the present invention to achieve high-stability phase locking with low computational complexity on low-computing-power MCUs (such as Cortex-M0 / M3 / M4) without relying on FPGAs, DSPs, or high-bandwidth processors. Since the iteration bandwidth of the MCU itself is limited, the present invention obtains the comprehensive performance of "fast convergence + low jitter in steady state + smooth output + real-time safety" through the collaborative coupling of trend perturbation, dual-mode hysteresis, triple constraint, and DMA timing, and can match common phase actuators (such as PZT fiber stretcher / phase modulator, etc.) and timer-driven DAC / ADC hardware beats, providing a feasible engineering solution for small MCU platforms to meet engineering applications.

[0059] The method described in the present invention is applicable to the fields of fiber optic interferometers, phase modulation / compensation, coherent detection, local oscillator drift suppression, and phase stabilization of free space / fiber optic links, and is also suitable for portable, miniaturized, and multi-channel optical phase regulation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0061] Figure 1 This is a flowchart of the optical phase control method described in Embodiment 1;

[0062] Figure 2 This is a schematic diagram of the dual-mode hysteresis method described in Implementation Method 1;

[0063] Figure 3 This is a flowchart of the error trend disturbance described in Implementation Method 4;

[0064] Figure 4 This is a schematic diagram of the triple constraint and adaptive update process described in Implementation Method 5;

[0065] Figure 5 This is a schematic diagram of the control system described in Implementation Method Six;

[0066] Figure 6 This is a timing diagram of synchronous acquisition and window measurement as described in Implementation Method Nine. Detailed Implementation

[0067] Various embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. The embodiments described with reference to the drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0068] Implementation Method 1: The optical phase control method described in this implementation method, such as... Figure 1 As shown, it includes the following steps:

[0069] Step S01, based on the target reference value of the optical phase V ref Initialize control variables u n and control parameters;

[0070] The control parameters include coarse control parameters and fine control parameters;

[0071] The coarse control parameters include the disturbance amplitude. d k and block length M The fine control parameters include the disturbance amplitude. d' and block length M’ ;

[0072] Step S02, Initialize the number of perturbations m =0, block correlation quantity S =0;

[0073] Step S03: Input a driving voltage to the phase actuator, acquire several detection voltage signals, and obtain a sampling sequence; based on the target reference value... V refUpdate the error amount using the obtained sampling sequence. e k Cost and the amplitude of the disturbance d k ;

[0074] The driving voltage pass

[0075]

[0076] Obtain, among which, ;

[0077] Step S04, based on the current error amount e k Select control parameters.

[0078] like If so, then the fine control parameter is selected as the selection control parameter;

[0079] like If so, then the coarse control parameter is selected as the selection control parameter;

[0080] in, T1 For fine error threshold, T2 This is a coarse error threshold. T1 < T2 ;

[0081] If the current control parameter is different from the selected control parameter, the current control parameter is replaced with the selected control parameter, and then step S02 is executed;

[0082] Otherwise, the number of perturbations is performed. m++ Block-related quantities Return to step S03 until... m M Proceed to step S05;

[0083] Step S05, if in the preceding consecutive M In the next iteration, the error amount e k If the error remains below the threshold and the control parameters remain fine, then the control of the optical phase is complete.

[0084] Otherwise, based on the current error amount e k Block correlation quantity Block length M and the amplitude of the disturbance d k For the control quantity u nPerform the update, return to step S02, and perform the next update.

[0085] In this embodiment, the error threshold is preferably a fine error threshold, which is the fine control parameter in embodiment five. T1。

[0086] In this embodiment, in step S01, the microcontroller (MCU) controls the DAC (digital-to-analog converter) module to output a scanning or sinusoidal excitation signal covering a preset voltage range to the phase actuator when the closed loop is not open, causing a phase change in the optical path; the detection voltage signal output by the optical detection module is sampled by the ADC (analog-to-digital converter) module under timer triggering, and the microcontroller (MCU) extracts the maximum value from the sampling sequence. Vmax and minimum value Vmin ,pass

[0087]

[0088] Obtain target reference value V ref .

[0089] The target reference value V ref Locking the operating point for subsequent closed-loop control.

[0090] In this embodiment, the control parameters include coarse control parameters and fine control parameters; relative to the coarse control parameters, the coarse control parameters include a larger disturbance amplitude. d k and smaller block length M .

[0091] In this embodiment, in step S04, when a switch in the control mode is detected (coarse mode)... When the model is fine, the microcontroller will measure the current disturbance amplitude. d k The adaptive update link is interrupted, and will d Reset to the disturbance amplitude saved from the last time this mode was used. d last To prevent during mode switching d Convergence disturbance imbalance caused by cross-modal misuse.

[0092] In this embodiment, the control parameter determination in step S04 is as follows: Figure 2 As shown, this method is a dual-mode switching mechanism with hysteresis characteristics, which satisfies the two requirements of "quickly entering the target area during the large deviation stage" and "maintaining a low jitter steady state near the target".

[0093] The control parameters described in this embodiment include coarse control parameters and fine control parameters. The coarse control parameters are applicable when the system deviates from the target reference value. V ref Larger phases are used to achieve rapid pullback; finer control parameters are suitable when the system is close to the target reference value. V ref The phase is to suppress jitter and maintain stability near the target.

[0094] Implementation Method Two: This implementation method further defines the optical phase control method described in Implementation Method One. In this implementation method, step S03 involves...

[0095]

[0096] Update error e k ,in, P k For voltage measurement;

[0097] voltage measurement P k pass

[0098]

[0099] Obtain, among which, The instantaneous voltage value read by the ADC; The first part of the sampling sequence There are 10 detected voltage signals, and the sampling sequence contains a total of 100 signals. One detection voltage signal.

[0100] This embodiment further defines step S03 and provides an example of the scheme in step S03. The first q samples are discarded in each frame, and the average of the last w samples is calculated to suppress transient interference during DAC update, actuator shifting, and ADC setup.

[0101] Implementation Method 3: This implementation method further defines the optical phase control method described in Implementation Method 1. In this implementation method, step S03 involves...

[0102]

[0103] Update cost ,in, P k For voltage measurement.

[0104] Implementation Method Four: This implementation method further defines the optical phase control method described in Implementation Method One. In this implementation method, step S03 involves...

[0105]

[0106] Update the disturbance amplitude, where, d min This is the lower limit of the disturbance amplitude. d max This is the upper limit of the disturbance amplitude. or The damping factor for the perturbation amplitude update law. S k Let be the phase-sensitive surrogate quantity, and sign() be the sign function.

[0107] In this embodiment, the phase sensitivity proxy quantity S k pass

[0108]

[0109] Obtain, among which, The maximum value extracted by the microcontroller (MCU) from this sampling sequence for the first time represents a phase difference between the two optical branches that is an integer multiple of 2π. The minimum value is extracted from the sampled sequence for the first time, representing an odd multiple of π in the phase difference between the two optical branches.

[0110] Phase sensitivity proxy S k The physical meaning of the slope of the interference curve.

[0111] In this embodiment, the damping factor of the disturbance amplitude update law or Used to control the adjustment rate of δ.

[0112] In this embodiment, the sign function sign() is used to reflect the trend of the current error compared to the previous step. If the error increases, it is +1; if it decreases, it is -1; and if it stabilizes, it is 0.

[0113] In this embodiment, the projection operator limits the perturbation amplitude to [δ]. min ,δ max Within the specified range, ensure system stability.

[0114] In this embodiment, the δ min pass

[0115]

[0116] Obtain, among which, This represents the minimum resolution of the DAC (Digital-to-Analog Converter) module, expressed in V. The sampling standard deviation of the ADC analog-to-digital conversion module is expressed in V. For the voltage conversion factor of the ADC analog-to-digital converter module, The sensitivity of the optical detection module is expressed in V / W.

[0117] , In this embodiment, the system's power supply voltage is... The voltage is the power supply voltage used by the microcontroller, for example, 3.3V, and n is the number of bits in the ADC analog-to-digital converter module.

[0118] In this embodiment, the δ max pass

[0119]

[0120] get.

[0121] This embodiment further defines step S03, and provides an example of the solution for step S03, such as... Figure 3 As shown, this embodiment introduces a disturbance amplitude memory and feedback update mechanism, that is, the disturbance amplitude is recorded in each disturbance. d k The next perturbation amplitude δ is calculated through error trend feedback. k+1 This enables dynamic evolution of disturbance intensity, improves the ability to match errors at different stages, enhances the adaptability and self-evolution of disturbance amplitude δ, and forms a self-feedback evolution link for disturbance amplitude.

[0122] In this embodiment, the control quantity u n After being converted by the DAC, the signal is directly applied to the phase actuator, causing a slight perturbation in the equivalent phase of the optical path. This phase change then induces a change in the intensity of the interference fringes, which is converted into a voltage signal by the photodetector. Therefore, the error... e k This is not an abstract numerical deviation, but a direct manifestation of the actual optical phase deviating from the reference operating point. Based on this, this implementation utilizes... e k Error compared to the previous shot e k-1 The trend quantity is used to determine whether "the previous phase perturbation pushed the system to move towards the target phase direction". Therefore, the trend quantity becomes the key closed-loop information connecting "phase response → perturbation adjustment", affecting the next perturbation δ. k+1 It can enhance or weaken based on the real dynamic changes in optical phase, forming a perturbation self-feedback link that is strongly coupled with the physical mechanism of optical phase.

[0123] Implementation Method Five: This implementation method further defines the optical phase control method described in Implementation Method One. In this implementation method, as... Figure 4 As shown, in step S05, based on the error amount e k Block correlation quantityS Block length M and the amplitude of the disturbance d k Obtain gradient and the smoothing error amount Based on the gradient and the smoothing error amount For the control quantity u n Adaptive step size, amplitude limiting, range projection, and smooth speed limiting are implemented to achieve updates;

[0124] The gradient pass

[0125]

[0126] get;

[0127] The smoothing error pass

[0128]

[0129] We obtain , where β is the smoothing coefficient.

[0130] In this embodiment, the smoothing coefficient β takes values ​​ranging from 1 to 10. Used to adjust the amount of smoothing error Weighting of historical and current errors. A larger β value results in... The stronger the memory of historical errors, the more obvious the smoothing effect, thus improving noise resistance; the smaller the β value, It responds faster to the current error, but is more sensitive to noise.

[0131] In this embodiment, by

[0132]

[0133] Obtain the step size, where K base Based on step size, c This is the step gain coefficient. K min This is the lower limit of the step size. K max `clip()` is the upper limit of the step size, and `clip()` is the clipping function. In a system with a 3.3V power supply and a 12-bit DAC, K min It can be taken as the voltage value corresponding to 1 to 3 DAC quantization steps. K max It can be taken as no more than 1% to 5% of the full scale, but this implementation method is not limited to this.

[0134] when Larger step sizes are allowed for faster pullback when the step size is larger. When the step size is small, the step size is automatically reduced to prevent overshoot and jitter, thereby obtaining an adaptive step size. In this embodiment, through...

[0135]

[0136] Obtain the original increment ;

[0137] pass

[0138]

[0139] Obtaining limited increments ,in, This is the maximum amplitude limit for a single step. for

[0140] .

[0141] This method obtains the original increment Then, a single-step amplitude limit is applied to the original increment to obtain the constrained increment. To suppress excessively large single jumps, the aforementioned amplitude limiting is achieved.

[0142] In this embodiment, by

[0143]

[0144] Obtain candidate values ;

[0145] pass

[0146]

[0147] get u lim in, clip() This is the amplitude limiting function.

[0148] This method will Δu clip Superimposed on the current control output u n The candidate value u is obtained above cand and u cand Projected onto the permissible operating voltage range of the phase actuator [U min U max ], thus obtaining the range-limited control quantity u lim This ensures that the physical driver is not driven out of bounds.

[0149] In this embodiment, if the current control parameter is a coarse control parameter, then for u... limApply coarse smoothing and speed limiting constraints. If the current control parameter is a fine control parameter, then for u... lim By applying fine smoothing and speed limiting constraints, high-frequency jitter can be further reduced and the phase actuator can be protected.

[0150] In this embodiment, by

[0151]

[0152] renew ,in, Used to limit the rate of change of a single step and to suppress mechanical or thermal resonance, 0 < α ≤ 1.

[0153] In this implementation, within the low-bandwidth closed loop dominated by the microcontroller (MCU), each perturbation-measurement-update cycle must be completed within a half-buffer period of DMA control / interrupt. This method avoids high-overhead computations such as matrix inversion, FFT, and numerical differentiation.

[0154] This embodiment further defines step S05, specifying the control quantity. u n The updated solution is illustrated with an example. By coupling the five elements of "error trend, disturbance amplitude, step size, limiting and smoothing", the maximum closed-loop performance is achieved with the fewest arithmetic operations, so that the low-bandwidth MCU still has the ability to quickly correct bias and stably lock phase when faced with noise and slow response phase changes.

[0155] Implementation method six, the optical phase control system described in this implementation method, such as Figure 5 As shown, the control system includes a microcontroller (MCU), a digital-to-analog converter (DAC), a phase actuator, an optical detection module, and an analog-to-digital converter (ADC).

[0156] The microcontroller (MCU) has an embedded computer program that executes an optical phase control method according to any one of embodiments one through five during runtime, and is used to convert the driving voltage obtained by the control method into a driving voltage. Send to the DAC (Digital-to-Analog Converter) module;

[0157] The DAC digital-to-analog converter module is used to convert the driving voltage The signal is converted into an analog signal and sent to the phase actuator.

[0158] The phase actuator is used to interfere with the optical path;

[0159] The optical detection module is used to detect the optical signal of the optical path and convert it into a detection voltage signal; it is also used to send the detection voltage signal to the ADC analog-to-digital converter module.

[0160] The ADC analog-to-digital converter module is used to convert the detected voltage signal into a digital signal; it is also used to send the digital signal to the microcontroller MCU as a detected voltage signal.

[0161] In this embodiment, the phase actuator is used to modulate or compensate the phase of the optical path, thereby affecting the interference state of the optical path.

[0162] Implementation Method Seven: This implementation method further defines the optical phase control system described in Implementation Method Six. In this implementation method, the microcontroller MCU further includes a timer TIM_DAC, which is used to control the DAC digital-to-analog conversion module to perform digital-to-analog conversion according to a predetermined cycle.

[0163] Implementation Method 8: This implementation method further defines the optical phase control system described in Implementation Method 6. In this implementation method, the microcontroller MCU further includes a timer TIM_ADC, which is used to control the ADC analog-to-digital conversion module to perform analog-to-digital conversion according to a predetermined sampling cycle.

[0164] Implementation Method Nine: This implementation method further defines the optical phase control system described in Implementation Method Six. In this implementation method, the microcontroller (MCU) further includes a DMA control / interrupt module. The DMA control / interrupt module is used to write the sampling sequence into the buffer through double buffering; and is also used to generate an interrupt signal to start the buffer reading operation when the buffer is half full.

[0165] In this embodiment, the starting position of the sampling sequence of the half-buffer of the buffer is... pass

[0166]

[0167] Obtain, among which, For semi-buffered indices, h∈{0,1}, The length of the sampling sequence Half of it.

[0168] When the half-buffered index When the value is 0, the sampling sequence is written to the first half of the buffer, and the half-buffer index... When the value is 1, the sampling sequence is written to the second half of the buffer.

[0169] This implementation uses a half-buffer setting to process the current sampling sequence while the next sampling is still in progress, achieving synchronous acquisition and window measurement timing. Figure 6 The figure shows a timing diagram of synchronous acquisition and window measurement.

[0170] This embodiment further defines the microcontroller (MCU) and provides an example of DMA control / interrupt. This method is a double-buffered mechanism. After each round of disturbance beats, the data of the current segment is processed to calculate the cost function and error signal, while the next segment of sampling is still in progress, forming a parallel operation of sampling and calculation.

[0171] This effectively avoids the occurrence of lost numbers and ensures the stability of the disturbance. d k Waveform output, ADC acquisition, cost J k Gradient estimation is strictly time-aligned to ensure reliable algorithm operation on the MCU. Without this method, ADC data will exhibit fragmented writing and reading behavior, with cost values ​​spanning multiple perturbation cycles, leading to errors in related accumulation terms. d k · J k Misalignment leads to randomization of gradient estimation directions, preventing the system from converging. Therefore, a double-buffering mechanism is the fundamental and key technical means to achieve perturbation-sampling synchronization, which can effectively improve the accuracy and speed of convergence.

Claims

1. An optical phase control method for an interferometric system, characterized in that, Includes the following steps: Step S01, based on the target reference value of the optical phase V ref Initialize control variables u n and control parameters; The control parameters include coarse control parameters and fine control parameters; The coarse control parameters include the disturbance amplitude. δ k and block length M The fine control parameters include the disturbance amplitude. δ' and block length M’ ; Step S02, Initialize the number of perturbations m =0, block correlation quantity S =0; Step S03: Input a driving voltage to the phase actuator, acquire several detection voltage signals, and obtain a sampling sequence; based on the target reference value... V ref Update the error amount using the obtained sampling sequence. e k Cost and the amplitude of the disturbance δ k ; The driving voltage pass Obtain, among which, ; Step S04, based on the current error amount e k Select control parameters. like If so, then the fine control parameter is selected as the selection control parameter; like If so, then the coarse control parameter is selected as the selection control parameter; in, T1 For fine error threshold, T2 This is a coarse error threshold. T1 < T2 ; If the current control parameter is different from the selected control parameter, the current control parameter is replaced with the selected control parameter, and then step S02 is executed; Otherwise, the number of perturbations is performed. m++ Block-related quantities Return to step S03 until... m M Proceed to step S05; Step S05, if in the preceding consecutive M In the next iteration, the error amount e k If the error remains below the threshold and the control parameters remain fine, then the control of the optical phase is complete. Otherwise, based on the current error amount e k Block correlation quantity Block length M and the amplitude of the disturbance δ k For the control quantity u n Perform the update, return to step S02, and perform the next update.

2. The optical phase control method according to claim 1, characterized in that, In step S03, through Update error e k ,in, P k For voltage measurement; voltage measurement P k pass Obtain, among which, The instantaneous voltage value read by the ADC; The first part of the sampling sequence There are 10 detected voltage signals, and the sampling sequence contains a total of 100 signals. One detection voltage signal.

3. The optical phase control method according to claim 1, characterized in that, In step S03, through Update cost ,in, P k For voltage measurement.

4. The optical phase control method according to claim 1, characterized in that, In step S03, through Update the disturbance amplitude, where, δ min This is the lower limit of the disturbance amplitude. δ max This is the upper limit of the disturbance amplitude. η The damping factor for the perturbation amplitude update law. S k Let be the phase-sensitive surrogate quantity, and sign() be the sign function.

5. The optical phase control method according to claim 1, characterized in that, In step S05, based on the error amount e k Block correlation quantity S Block length M and the amplitude of the disturbance δ k Obtain gradient and smoothing error Based on the gradient and the smoothing error amount For the control quantity u n Adaptive step size, amplitude limiting, range projection, and smooth speed limiting are implemented to achieve updates; The gradient pass get; The smoothing error pass We obtain , where β is the smoothing coefficient.

6. An optical phase control system for an interferometric system, characterized in that, The control system includes a microcontroller (MCU), a digital-to-analog converter (DAC), a phase actuator, an optical detection module, and an analog-to-digital converter (ADC). The microcontroller (MCU) has an embedded computer program that executes the optical phase control method according to any one of claims 1 to 5 during runtime, and is used to convert the driving voltage obtained by the control method into a driving voltage. Send to the DAC (Digital-to-Analog Converter) module; The DAC digital-to-analog converter module is used to convert the driving voltage The signal is converted into an analog signal and sent to the phase actuator. The phase actuator is used to interfere with the optical path; The optical detection module is used to detect the optical signal of the optical path and convert it into a detection voltage signal; it is also used to send the detection voltage signal to the ADC analog-to-digital converter module. The ADC analog-to-digital converter module is used to convert the detected voltage signal into a digital signal; it is also used to send the digital signal to the microcontroller MCU as a detected voltage signal.

7. The optical phase control system according to claim 6, characterized in that, The microcontroller MCU also includes a timer TIM_DAC, which is used to control the DAC digital-to-analog conversion module to perform digital-to-analog conversion according to a predetermined cycle.

8. The optical phase control system according to claim 6, characterized in that, The microcontroller MCU also includes a timer TIM_ADC, which is used to control the ADC analog-to-digital conversion module to perform analog-to-digital conversion according to a predetermined sampling cycle.

9. The optical phase control system according to claim 6, characterized in that, The microcontroller (MCU) also includes a DMA control / interrupt module, which is used to write the sampling sequence into a buffer through double buffering; and to generate an interrupt signal to start a buffer read operation when the buffer is half full.

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