A method and system for cooperative braking of a nonlinear microscopic imaging fiber scanner

Abstract

The application discloses a kind of cooperative braking method and system of nonlinear microscopic imaging fiber scanner, method includes obtaining and based on X-axis correction angle and Y-axis correction angle, obtain the coordinate transformation relationship after error compensation;Obtain and based on system resonance frequency and quality factor, determine the range of brake pulse width;The range of phase interval is 150°~210°;With brake phase as scanning variable, phase scanning experiment is carried out, and the optimal brake phase is determined;Based on system resonance frequency, quality factor, optimal brake phase and preset candidate envelope function, determine the optimal envelope function;At the moment of spiral scanning termination, brake waveform is generated;When brake pulse reaches preset brake moment, brake signal is forced to zero, so that the system enters free decay state.The application brake speed is fast, anti-system drift, spectral pure, adaptive capacity is strong, applicable to nonlinear microscopic, fiber endoscopy spiral scanning imaging system.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric drive and precision optical scanning control technology, specifically to a cooperative braking method and system for a nonlinear microscopic imaging fiber optic scanner. Background Technology

[0002] The fiber optic scanner for nonlinear microscopy is the core component of fiber optic nonlinear microscopy. Its working principle involves driving the end of a hollow antiresonant fiber in a helical trajectory using a piezoelectric ceramic tube. A position-sensitive detector (PSD) monitors and provides feedback on the fiber end position in real time, enabling high-resolution nonlinear imaging. At the end of each helical scan, the hollow antiresonant fiber must be rapidly braked from its high-speed helical motion to a stationary state to ensure consistent initial conditions for the next scan frame. The braking performance directly affects the imaging frame rate and image quality.

[0003] The braking of nonlinear microscopic fiber optic scanners faces unique physical constraints: the system resonant frequency. Typically in the hundreds of hertz range, the quality factor... A relatively high value (typically 50~100) corresponds to a natural decay time constant. The amplitude decays to approximately tens of milliseconds, and it takes hundreds of milliseconds for the amplitude to naturally decay back to 5% of its peak value. Relying solely on passive waiting would severely limit the imaging frame rate. Therefore, active braking technology is a core technology in this field.

[0004] Existing active braking technologies generally employ an envelope braking method based on phase reversal drive, where the braking signal is controlled to be 180° out of phase with the current drive signal (i.e., phase reversal). This method cancels out fiber vibration energy by applying a decaying envelope signal. However, this method has the following inherent drawbacks:

[0005] (1) Poor parameter robustness of 180° reverse-phase braking: From a physical mechanism perspective, the relationship between braking efficiency and braking phase is influenced by factors. The decision, in At 180°, It reaches a maximum value of 1, but its derivative... exist =180° is exactly zero, which is in the sharp peak region of the envelope curve. This means that any tiny phase jitter or frequency shift will cause the braking performance to degrade in one direction. Since this point is a maximum point, the degradation cannot be compensated by fine-tuning the phase. The performance loss can only be passively accepted. This places stringent requirements on the system stability, which is difficult to meet in practical applications.

[0006] (2) Harmonic pollution caused by 180° splicing: When the waveforms of the braking section and the driving section are connected at the splicing point, the 180° out-of-phase splicing will inevitably introduce a signal abrupt change - equivalent to superimposing a square wave component at the splicing point. Fourier analysis shows that this square wave component contains significant odd harmonics. , , ...), these harmonics will excite higher-order vibration modes of piezoelectric ceramics, causing braking energy to be transferred from the target fundamental frequency to high-frequency parasitic modes instead of being effectively dissipated, thus prolonging the actual braking time. Moreover, high-frequency parasitic vibrations will also introduce additional mechanical noise, affecting system stability;

[0007] (3) Low energy efficiency of continuous envelope braking: Existing methods generally output a decaying envelope signal continuously within the braking window. However, experiments show that the residual amplitude of the system drops to the PSD noise level after a short decay. After that, the application of the braking signal has no substantial effect on the residual vibration, but continues to consume driving energy, resulting in unnecessary energy waste and system heating.

[0008] Therefore, a collaborative braking scheme for nonlinear microscopic imaging fiber scanners is needed to achieve rapid suppression of residual vibration through collaborative optimization of braking phase and envelope curve, in order to solve the above problems. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a cooperative braking method and system for a nonlinear microscopic imaging fiber optic scanner, so as to solve the technical problems of poor parameter robustness, harmonic pollution and low energy efficiency of the existing braking technology.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] According to a first aspect of the present invention, a method for coordinated braking of a nonlinear microscopic imaging fiber optic scanner is provided, the method comprising the following steps:

[0012] Obtain the X-axis correction angle and Y-axis correction angle, and based on the X-axis correction angle and Y-axis correction angle, construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system to obtain the coordinate transformation relationship after error compensation;

[0013] Obtain the system resonant frequency and quality factor, and determine the range of braking pulse width based on the system resonant frequency and quality factor;

[0014] Obtain the range of the phase interval, which is 150°~210°;

[0015] With a fixed braking pulse width, a phase scanning experiment is conducted using the braking phase as the scanning variable to determine the optimal braking phase, wherein the optimal braking phase is within the phase interval.

[0016] The optimal envelope function is determined based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions.

[0017] At the moment the helical scan terminates, a braking waveform is generated based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width.

[0018] When the braking pulse reaches the preset braking moment, the braking signal is forced to zero, allowing the system to enter a free decay state.

[0019] In this invention, preferably, obtaining the X-axis correction angle and the Y-axis correction angle includes:

[0020] Single-axis response data for the X-axis and single-axis response data for the Y-axis are collected separately to obtain X-axis data and Y-axis data respectively;

[0021] Ellipse least squares fitting was performed on the X-axis and Y-axis data respectively to obtain the X-axis fitted ellipse parameters and the Y-axis fitted ellipse parameters respectively.

[0022] Based on the X-axis and Y-axis fitted ellipse parameters, the X-axis correction angle and Y-axis correction angle are obtained.

[0023] In this invention, preferably, the asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system based on the X-axis correction angle and the Y-axis correction angle, to obtain the coordinate transformation relationship after error compensation, includes:

[0024] The coordinate transformation relationship after error compensation is expressed by the following formula:

[0025]

[0026]

[0027] in, For X-axis correction angle, For the Y-axis correction angle, These are the coordinate parameters before X-axis correction. These are the coordinate parameters after X-axis correction. These are the coordinate parameters before Y-axis correction. These are the Y-axis corrected coordinate parameters.

[0028] In this invention, preferably, obtaining the system resonant frequency and quality factor includes:

[0029] A frequency sweep experiment was conducted within the preset resonant frequency range to obtain steady-state amplitude data at each frequency point, thereby obtaining amplitude-frequency data.

[0030] Lorentzian fitting was performed on the amplitude-frequency data to obtain the system's resonant frequency and full width at half maximum (FWHM) parameter.

[0031] Based on the system resonant frequency and full width at half maximum (FWHM) parameter, the first quality factor to be tested is obtained;

[0032] The second quality factor to be tested is obtained based on the system's resonant frequency using the attenuation method.

[0033] The first quality factor to be inspected and the second quality factor to be inspected are cross-validated to obtain the quality factor.

[0034] In this invention, preferably, the range of the obtained phase interval includes:

[0035] Obtain permissible braking performance parameters;

[0036] Obtain the braking efficiency and sensitivity values ​​corresponding to each phase;

[0037] Based on the braking efficiency and sensitivity values ​​corresponding to each phase, the upper and lower boundaries of the phase interval are determined to obtain the range of the phase interval.

[0038] In this invention, preferably, the fixed braking pulse width, using the braking phase as the scanning variable to perform a phase scanning experiment to determine the optimal braking phase, includes:

[0039] Under the conditions of fixed system resonant frequency, driving amplitude and braking pulse width, the braking phase is used as the scanning variable to traverse the range from 0° to 360°.

[0040] Obtain the main evaluation index value and auxiliary verification index value for each phase;

[0041] The phase corresponding to the smallest main evaluation index value is selected as the optimal braking phase.

[0042] In this invention, preferably, the preset candidate envelope function includes power-law decay, exponential decay, S-curve, smooth S-curve, parabolic decay, inverse parabolic decay, step decay, oscillatory decay, logarithmic decay, and linear decay.

[0043] In this invention, preferably, determining the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions includes:

[0044] Under the condition of fixed optimal braking phase and braking pulse width, the preset candidate envelope functions are tested respectively, and the ranking table of the main evaluation index values ​​corresponding to each candidate envelope function is obtained.

[0045] The optimal envelope function is determined based on a ranking table of the system resonant frequency, quality factor, and the main evaluation index values ​​corresponding to each candidate envelope function.

[0046] In this invention, preferably, the step of generating a braking waveform at the helical scan termination time based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width includes:

[0047] The braking waveform is represented by the following formula:

[0048] ,

[0049] in, This is the braking waveform. This is the braking amplitude. For the optimal envelope function, For the optimal braking phase, The system resonant frequency, The time when the helical scan terminates. This represents the braking pulse width.

[0050] According to a second aspect of the present invention, a cooperative braking system for a nonlinear microscopic imaging fiber optic scanner is provided for performing the cooperative braking method of the nonlinear microscopic imaging fiber optic scanner described in any of the above claims. The system includes a computer control and processing unit, a data acquisition card, a drive execution unit, and a position-sensitive detector.

[0051] The data acquisition card is connected to the computer control and processing unit and is used to acquire single-axis response data of the X-axis and single-axis response data of the Y-axis, as well as intermediate data in the cooperative braking method, according to the digital control instructions issued by the computer control and processing unit, and feed them back to the computer control and processing unit.

[0052] The drive execution unit is connected to the analog output channel of the data acquisition card and is used to execute corresponding operations according to the analog instructions output by the analog output channel of the data acquisition card;

[0053] The position-sensitive detector is connected to the data acquisition card and is used to send three photocurrent signals to the analog input channel of the data acquisition card;

[0054] The computer control and processing unit includes an error compensation module, a system parameter determination module, an optimal braking determination module, an envelope function filtering module, a braking waveform generation module, and a zeroing control module.

[0055] The error compensation module is used to obtain the X-axis correction angle and the Y-axis correction angle, and based on the X-axis correction angle and the Y-axis correction angle, to construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system, and obtain the coordinate transformation relationship after error compensation.

[0056] The system parameter determination module is used to obtain the system resonant frequency and quality factor, and based on the system resonant frequency and quality factor, to determine the range of braking pulse width;

[0057] The optimal braking determination module is used to obtain the range of the phase interval, fix the braking pulse width, and perform a phase scanning experiment with the braking phase as the scanning variable to determine the optimal braking phase;

[0058] The envelope function filtering module is used to determine the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions.

[0059] The braking waveform generation module is used to send braking control commands to the digital acquisition card at the end of the helical scan, and generate a braking waveform based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width.

[0060] The zero-reset control module is used to force the braking signal to zero when the braking pulse reaches the preset braking moment, and to reset the digital control command sent to the data acquisition card to zero, so that the system enters the free decay state.

[0061] Compared with existing technologies, the beneficial effects of this invention are as follows: By acquiring the X-axis and Y-axis correction angles, an asymmetric rotational transformation from the virtual driving coordinate system to the actual physical coordinate system is constructed, resulting in the coordinate transformation relationship after error compensation. The independent calibration mechanism of the dual correction angles makes this method applicable to various piezoelectric scanner geometries, eliminating the need for precise mechanical alignment and reducing the difficulty of system assembly and adjustment. By determining the system resonant frequency and quality factor, the range of braking pulse width is determined, ensuring that the braking pulse width is within the optimal range, providing a prerequisite for subsequent efficient braking. By determining the range of the phase interval and conducting phase scanning experiments with the braking phase as the scanning variable, the optimal braking phase is determined, ensuring that the selected optimal braking phase is the best value of the system under the current conditions, enhancing the stability and consistency of braking. By determining the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions, the optimal envelope function is determined, allowing for different... The system flexibly selects the optimal envelope shape, and the adjustable parameters of the nonlinear envelope provide sufficient freedom for waveform optimization under different working conditions, making the invention highly adaptive. By generating a braking waveform at the end of the spiral scan based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width, the invention ensures that the braking segment and the driving segment maintain the continuity of the sinusoidal waveform at the splicing point, with no voltage abrupt change at the splicing point, equivalent to a pure sinusoidal splicing. This concentrates all braking energy on the target fundamental frequency mode, avoids the excitation of higher-order parasitic modes, and shortens the actual braking time. By forcibly returning the braking signal to zero when the braking pulse reaches the preset braking time, the system enters a free decay state, reducing the consumption of braking energy. The "pulse-release" strategy saves energy significantly without sacrificing braking speed, avoiding the technical problems of poor parameter robustness, harmonic pollution, and low energy efficiency of existing braking technologies. Attached Figure Description

[0062] Figure 1 A schematic diagram of the main structure of a cooperative braking system for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention;

[0063] Figure 2 A timing flowchart illustrating a cooperative braking method for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention;

[0064] Figure 3 A schematic diagram of the main process of a cooperative braking method for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention;

[0065] Figure 4 for A schematic diagram of the function curve and its derivative curve;

[0066] Figure 5 A schematic diagram comparing the morphology of ten braking envelope functions for a cooperative braking method of a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention.

[0067] Figure 6 A bar chart comparing the braking effects of ten envelope functions in a cooperative braking method for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention.

[0068] Figure 7 A schematic diagram comparing the envelope evolution of 150°~210° braking and 180° anti-phase braking in a cooperative braking method for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention.

[0069] Figure 8A schematic diagram comparing the spectrum of the 150°~210° and 180° spliced ​​waveforms of a cooperative braking method for a nonlinear microscopic imaging fiber optic scanner provided in an embodiment of the present invention. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0072] This invention designs a cooperative braking method and system for a nonlinear microscopic imaging fiber optic scanner. By limiting the optimal braking phase to a linearly adjustable range of 150° to 210°, phase deviation can be compensated bidirectionally, and waveform splicing is seamless without abrupt changes or odd harmonics. A family of nonlinear envelope functions containing ten attenuation curves is constructed to achieve efficient braking. A pulse-release timing sequence is employed, with forced zeroing after the braking pulse ends, relying on system damping for free attenuation to reduce ineffective drive energy consumption. This invention results in fast braking speed, resistance to system drift, spectral purity, and strong adaptability, making it suitable for nonlinear microscopy and fiber optic endoscopic spiral scanning imaging systems. (See also...) Figures 2 to 8 A preferred embodiment of the present invention provides a method for coordinated braking of a nonlinear microscopic imaging fiber optic scanner, the method comprising the following steps:

[0073] Step S101: Obtain the X-axis correction angle and Y-axis correction angle, and based on the X-axis correction angle and Y-axis correction angle, construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system to obtain the coordinate transformation relationship after error compensation;

[0074] In some embodiments, obtaining the X-axis correction angle and the Y-axis correction angle includes:

[0075] Single-axis response data for the X-axis and single-axis response data for the Y-axis are collected separately to obtain X-axis data and Y-axis data respectively;

[0076] Ellipse least squares fitting was performed on the X-axis and Y-axis data respectively to obtain the X-axis fitted ellipse parameters and the Y-axis fitted ellipse parameters respectively.

[0077] Based on the X-axis and Y-axis fitted ellipse parameters, the X-axis correction angle and Y-axis correction angle are obtained.

[0078] In some embodiments, before obtaining the X-axis correction angle and the Y-axis correction angle, the method further includes: applying a standard sine drive to the X-axis and setting the Y-axis drive to zero.

[0079] In some embodiments, obtaining the X-axis correction angle and the Y-axis correction angle specifically includes:

[0080] After applying a standard sine drive to the X-axis and setting the Y-axis drive to zero, the X / Y axis responses of the position-sensitive detector PSD are acquired.

[0081] Perform elliptic least squares fitting on the collected data;

[0082] The principal axis inclination angle can be obtained by calculating the parameters of the fitted ellipse. Similarly, a standard sine drive is applied to the Y-axis to determine... ;

[0083] Here, by setting and This compensates for the asymmetry of the X / Y axis mechanical properties of the piezoelectric bicrystalline wafer and the deviation of the PSD mounting angle.

[0084] In some embodiments, the asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system based on the X-axis correction angle and the Y-axis correction angle, to obtain the coordinate transformation relationship after error compensation, includes:

[0085] The coordinate transformation relationship after error compensation is expressed by the following formula:

[0086]

[0087]

[0088] in, For X-axis correction angle, For the Y-axis correction angle, These are the coordinate parameters before X-axis correction. These are the coordinate parameters after X-axis correction. These are the coordinate parameters before Y-axis correction. These are the Y-axis corrected coordinate parameters.

[0089] In the above embodiments, dual correction angles The independent calibration mechanism makes this method applicable to various piezoelectric scanner geometries, eliminating the need for precise mechanical alignment, reducing the difficulty of system assembly and adjustment, and enabling the invention to achieve good compatibility.

[0090] Step S102: Obtain the system resonant frequency and quality factor, and determine the range of braking pulse width based on the system resonant frequency and quality factor;

[0091] In some embodiments, obtaining the system resonant frequency and quality factor includes:

[0092] A frequency sweep experiment was conducted within the preset resonant frequency range to obtain steady-state amplitude data at each frequency point, thereby obtaining amplitude-frequency data.

[0093] Lorentzian fitting was performed on the amplitude-frequency data to obtain the system's resonant frequency and full width at half maximum (FWHM) parameter.

[0094] Based on the system resonant frequency and full width at half maximum (FWHM) parameter, the first quality factor to be tested is obtained;

[0095] The second quality factor to be tested is obtained based on the system's resonant frequency using the attenuation method.

[0096] The first quality factor to be inspected and the second quality factor to be inspected are cross-validated to obtain the quality factor.

[0097] In some embodiments, obtaining the system resonant frequency and quality factor specifically includes:

[0098] A frequency sweeping method is used to sweep the frequency in the vicinity of the resonant frequency (which can be 250-400Hz) with a fine step size (which can be 0.5Hz). The steady-state amplitude at each frequency point is recorded, and Lorentzian fitting is performed on the amplitude-frequency data to obtain the system resonant frequency. and half-height and full-width parameters ;

[0099] Based on the system resonant frequency and half-height and full-width parameters ,calculate The first quality factor to be tested is obtained.

[0100] Simultaneously, the Ringdown method is used for cross-validation: at the operating amplitude and the system resonant frequency. After the drive reaches steady state, it is suddenly turned off. An exponential decay fit is performed on the decay envelope, and the following calculations are made. Thus, the second quality factor to be tested is obtained;

[0101] The two methods are mutually verified to ensure The value measurement is accurate.

[0102] Step S103: Obtain the range of the phase interval, wherein the range of the phase interval is 150°~210°;

[0103] In some embodiments, obtaining the range of the phase interval includes:

[0104] Obtain permissible braking performance parameters;

[0105] Obtain the braking efficiency and sensitivity values ​​corresponding to each phase;

[0106] Based on the braking efficiency and sensitivity values ​​corresponding to each phase, the upper and lower boundaries of the phase interval are determined to obtain the range of the phase interval.

[0107] In some embodiments, the range of the phase interval to be obtained specifically includes:

[0108] The lower and upper bounds of the phase interval are selected based on the following two engineering criteria:

[0109] (1) Performance threshold criterion: braking performance and Proportional to the actual braking efficiency, with a certain value representing an efficiency not lower than the ideal peak value (180°) as the engineering threshold. That is, when the allowable braking efficiency parameter is 85%, due to... That is, the braking efficiency is not less than 86.6% of the peak value. Therefore, 150° is the lower boundary of the phase interval and 210° is the upper boundary of the phase interval. Alternatively, when the allowable braking efficiency parameter is 50%, the lower and upper boundaries of the phase interval are widened to 120°~240°.

[0110] (2) Sensitivity balance criterion: based on The value is determined by the derivative of the change. At 150° absolute value of the derivative This indicates that for every 1° phase deviation, the efficiency changes by approximately 0.87%. This derivative value is moderate, providing sufficient sensitivity for phase compensation to avoid the problem of being too small to detect phase shifts, while also avoiding being too sensitive to cause overcompensation oscillations.

[0111] In the above embodiments, the present invention selects the braking phase in the range of 150° to 210°, which is located in... Linear segment of the curve ( When the braking phase fluctuates slightly due to factors such as temperature drift, PZT hysteresis, or frequency deviation, the 150°~210° range can be actively compensated for by bidirectional phase adjustment to maintain stable braking performance; while traditional 180° reverse-phase braking is in a state of... At the peak point (where the derivative is zero), the phase error can only lead to irreversible performance degradation, which cannot be recovered by adjustment, thus enabling the present invention to achieve fast braking with strong stability.

[0112] Step S104: Fix the braking pulse width, perform a phase scanning experiment with the braking phase as the scanning variable, and determine the optimal braking phase, wherein the optimal braking phase is within the phase interval.

[0113] In some embodiments, the fixed braking pulse width, using the braking phase as the scanning variable to perform a phase scanning experiment to determine the optimal braking phase, includes:

[0114] Under the conditions of fixed system resonant frequency, driving amplitude and braking pulse width, the braking phase is used as the scanning variable to traverse the range from 0° to 360°.

[0115] Obtain the main evaluation index value and auxiliary verification index value for each phase;

[0116] The phase corresponding to the smallest main evaluation index value is selected as the optimal braking phase.

[0117] In some embodiments, the fixed braking pulse width, using the braking phase as the scanning variable to perform a phase scanning experiment to determine the optimal braking phase, specifically includes:

[0118] With a fixed system resonant frequency Drive amplitude and braking pulse width Under the condition of braking phase The scanning variable traverses within the range of 0° to 360°. The step size can be set to 30° for fine scanning or smaller for fine scanning. Multiple complete cycles are collected for each phase condition to ensure statistical validity.

[0119] Using ts_5% of the braking stop period as the main evaluation index, and the root mean square of the residual speed after braking as the metric. As an auxiliary verification indicator, the phase corresponding to the minimum value of ts_5% is selected as the optimal braking phase. The definitions of each indicator are as follows:

[0120] The ts_5% is defined as: the vibration envelope amplitude at the moment of braking initiation. Calculate the 5% threshold line as a reference peak value. From the moment braking begins, the search continues until the envelope amplitude is consistently lower than the specified value. And the first moment ts_5% of the duration is ≥3 resonance cycles;

[0121] The Defined as: the PSD normalized position signal within 5 resonant cycles after braking ends. , The velocity at each sampling point was calculated using the central difference method. , , .

[0122] In the above embodiments, phase scan results show that ts_5% reaches its global minimum in the 150°~210° range, verifying the effectiveness of the phase range selected in this invention; auxiliary indicators The fact that the phases are basically equal indicates that the difference in braking phases is mainly reflected in the decay rate rather than the final residual amplitude, thus confirming the rationality of the "pulse-release" strategy: regardless of the phase, the system can eventually be driven to the same residual level, but the optimal phase can complete this process at the fastest speed.

[0123] In some embodiments, such as Figure 4 As shown, The function curve is It reaches a maximum value of 1 at 180°, but its derivative At this point, the value is exactly zero, which is the peak of the curve—meaning that the phase deviation at 180° can only cause a one-way degradation in braking performance; while the 150°~210° range is located at... In the linear region of the curve, the derivative is significantly non-zero, and the phase error can be actively compensated through bidirectional adjustment. Under this physical mechanism, in the 150°~210° range, the braking signal does work along the tangent direction of the vibration ellipse trajectory, achieving an optimal balance between anti-phase energy cancellation and positive damping, thus obtaining the fastest amplitude decay, reflecting... =150°~210° interval (linear region where the derivative is non-zero) and =180° (the peak point where the derivative is zero), demonstrating the mathematical nature of the differences in parameter robustness.

[0124] Step S105: Determine the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions;

[0125] In some embodiments, the preset candidate envelope function includes power-law decay, exponential decay, sigmoid curve, smooth sigmoid curve, parabolic decay, inverse parabolic decay, step decay, oscillatory decay, logarithmic decay, and linear decay.

[0126] In some embodiments, the optimal envelope function The following candidate envelope functions are selected from the preset pool:

[0127] (1) Power-law decay: , The convex function shape achieves "fast at first, slow later" braking;

[0128] (2) Exponential decay: It has strong initial braking force;

[0129] (3) S-shaped curve: The start and end segments transition smoothly;

[0130] (4) Smooth S-curve: Smooth throughout;

[0131] (5) Parabolic decay: Concave function shape;

[0132] (6) Inverse parabolic attenuation: convex function shape;

[0133] (7) Step decay: , Switch-type braking;

[0134] (8) Oscillation decay: Utilizing periodic dissipation;

[0135] (9) Logarithmic decay: Logarithmic law slows down;

[0136] (10) Linear decay: Deceleration is gradual.

[0137] The ten envelope functions mentioned above can be systematically compared and screened to select the optimal envelope shape to suit different needs. Value system, high The system selects a convex function to enhance initial braking and reduce low The system uses a gentle curve to avoid overshoot.

[0138] In some embodiments, such as Figure 5 As shown, the ten envelope functions exhibit different decay curve shapes on the normalized time axis: power-law decay ( The inverse parabolic attenuation exhibits a convex function shape, with a slow descent in the initial braking phase and an acceleration to zero in the later braking phase; the parabolic attenuation exhibits a concave function shape with the opposite trend; linear attenuation has a uniform transition; and the S-shaped curve changes smoothly at the beginning and end, and decreases rapidly in the middle.

[0139] In some embodiments, with a fixed optimal braking phase and braking pulse width Under the given conditions, ten envelope functions were tested; each envelope function was measured repeatedly under the same experimental conditions, with ts_5% used as the primary evaluation index.

[0140] like Figure 6 As shown, experimental results indicate that convex function envelopes (power-law decay α<1, inverse parabolic decay, etc.) have the shortest braking time, followed by linear envelopes, while concave function envelopes (parabolic decay) are relatively less effective. The physical reason why convex function envelopes are superior to linear envelopes is that the amplitude is large in the initial braking stage, requiring a high-amplitude braking signal to quickly offset the energy; the amplitude is small in the later braking stage, requiring a reduction in braking amplitude to avoid overshoot excitation—convex function shapes precisely meet this "fast at first, slow later" requirement. Among them, power-law decay... , It performs best among the ten candidate envelopes, with its convexity index being the highest. Systematic experiments can be used to perform fine-grained optimization on specific systems.

[0141] In the above embodiments, the envelope family consisting of ten envelope functions allows for different... The value system flexibly selects the optimal envelope shape: high The system selects a convex function envelope (which can be power-law decay, α<1) to enhance the initial braking force; low The system selects a gentle envelope (which can be linearly decaying) to avoid overshoot excitation. The adjustable parameters of the nonlinear envelope provide ample freedom for waveform optimization under different operating conditions, making this invention highly adaptive.

[0142] Step S106: At the end of the helical scan, based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width, a braking waveform is generated.

[0143] In some embodiments, generating a braking waveform at the helical scan termination time, based on the error-compensated coordinate transformation relationship, system resonant frequency, optimal braking phase, optimal envelope function, optimal braking phase, and braking pulse width, includes:

[0144] The braking waveform is represented by the following formula:

[0145] ,

[0146] in, This is the braking waveform. For braking amplitude, For the optimal envelope function, For the optimal braking phase, The system resonant frequency, The time when the helical scan terminates. This represents the braking pulse width.

[0147] In the above embodiment, the 150°~210° braking phase ensures the continuity of the sinusoidal waveform between the braking segment and the driving segment at the splicing point, with no voltage abrupt change at the splicing point, equivalent to a pure sinusoidal splicing, i.e., the spectrum contains only the fundamental frequency component. It does not generate odd harmonic components; the braking energy is all concentrated on the target fundamental frequency mode, avoiding the excitation of higher-order parasitic modes, shortening the actual braking time, and enabling the invention to achieve harmonic pollution-free operation.

[0148] Step S107: When the braking pulse reaches the preset braking moment, the braking signal is forced to zero, so that the system enters the free decay state, that is, the residual energy is naturally dissipated by material internal friction and air damping.

[0149] In some embodiments, when the braking pulse reaches a preset braking moment, the braking signal is forcibly returned to zero, allowing the system to enter a free decay state, including:

[0150] exist At that moment, the braking signal is forced to zero, and the system enters a free decay state, utilizing material internal friction and air damping to complete the natural dissipation of residual energy.

[0151] Wherein, the braking pulse width Selected as to The lower limit is determined by the minimum time required for energy cancellation (covering at least one half-resonance cycle), and the upper limit is determined by the PSD noise background level. Braking stops when the residual amplitude has decreased to the noise background, based on typical system parameters. The preferred value corresponds to several resonant cycles.

[0152] In some embodiments, such as Figure 2 As shown, the method specifically includes three time periods: the spiral drive segment ( ), braking pulse segment ( ), Zero-release segment ( ):

[0153] In the spiral drive section ( In the process, a spiral scanning sinusoidal drive waveform is continuously output, and the fiber optic steady-state spiral scanning is achieved.

[0154] During the braking pulse segment ( In the above, t=0: the scan ends, the braking waveform generation is started, and the braking pulse with nonlinear envelope and phase of 150°~210° is output;

[0155] In the zero-release phase ( In the above, t=T_pulse: the braking signal forces the light to zero, and the optical fiber decays freely to rest due to mechanical damping.

[0156] In the above embodiments, the present invention adopts a "pulse-release" strategy, which outputs a brief braking pulse (several resonant cycles) only in the initial stage of braking, after which the system decays freely. Compared with the traditional continuous braking method, the braking energy consumption of the present invention is significantly reduced. This is because the system amplitude has dropped to the noise floor in the later stage of braking, and continuing to apply the braking signal has no substantial suppression effect. The "pulse-release" strategy saves energy significantly without sacrificing braking speed, making the present invention highly energy efficient.

[0157] Furthermore, the present invention also provides a cooperative braking system for a nonlinear microscopic imaging fiber optic scanner.

[0158] See appendix Figure 1 , Figure 1 This is a schematic diagram of the main structure of a cooperative braking system for a nonlinear microscopic imaging fiber optic scanner according to an embodiment of the present invention. Figure 1 As shown in the embodiment of the present invention, a cooperative braking system for a nonlinear microscopic imaging fiber optic scanner is used to execute the aforementioned cooperative braking method for the nonlinear microscopic imaging fiber optic scanner. The cooperative braking system for the nonlinear microscopic imaging fiber optic scanner includes a computer control and processing unit, a data acquisition card, a drive execution unit, and a position-sensitive detector.

[0159] The data acquisition card is connected to the computer control and processing unit and is used to acquire single-axis response data of the X-axis and single-axis response data of the Y-axis, as well as intermediate data in the cooperative braking method, according to the digital control instructions issued by the computer control and processing unit, and feed them back to the computer control and processing unit.

[0160] The drive execution unit is connected to the analog output channel of the data acquisition card and is used to execute corresponding operations according to the analog instructions output by the analog output channel of the data acquisition card;

[0161] The position-sensitive detector is connected to the data acquisition card and is used to send three photocurrent signals to the analog input channel of the data acquisition card;

[0162] The computer control and processing unit includes an error compensation module, a system parameter determination module, an optimal braking determination module, an envelope function filtering module, a braking waveform generation module, and a zeroing control module.

[0163] The error compensation module is used to obtain the X-axis correction angle and the Y-axis correction angle, and based on the X-axis correction angle and the Y-axis correction angle, to construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system, and obtain the coordinate transformation relationship after error compensation.

[0164] The system parameter determination module is used to obtain the system resonant frequency and quality factor, and based on the system resonant frequency and quality factor, to determine the range of braking pulse width;

[0165] The optimal braking determination module is used to obtain the range of the phase interval, fix the braking pulse width, and perform a phase scanning experiment with the braking phase as the scanning variable to determine the optimal braking phase;

[0166] The envelope function filtering module is used to determine the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions.

[0167] The braking waveform generation module is used to send braking control commands to the digital acquisition card at the end of the helical scan, and generate a braking waveform based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width.

[0168] The zero-reset control module is used to force the braking signal to zero when the braking pulse reaches the preset braking moment, and to reset the digital control command sent to the data acquisition card to zero, so that the system enters the free decay state.

[0169] In some embodiments, the drive execution unit includes a piezoelectric ceramic bicrystalline driver, a single-mode optical fiber, and a collimating lens. The analog output channel of the data acquisition card outputs a dual-channel analog virtual voltage to the piezoelectric ceramic bicrystalline driver. The piezoelectric ceramic bicrystalline driver is fixed at the end of the single-mode optical fiber. The piezoelectric ceramic bicrystalline driver drives the end of the single-mode optical fiber to scan in a spiral trajectory. The single-mode optical fiber outputs a scanning beam to the collimating lens. The collimating lens is disposed on the outgoing light path of the single-mode optical fiber. The outgoing light from the optical fiber is focused by the collimating lens onto the photosensitive surface of the two-dimensional position-sensitive detector to collimate the scanning beam emitted from the single-mode optical fiber.

[0170] In some embodiments, the position-sensitive detector (PSD) is placed on the outgoing optical path of the collimating lens, receives the collimated scanning beam, and outputs three photocurrent signals to the analog input channel of the data acquisition card. The position-sensitive detector is used to monitor the actual position of the end of the feedback optical fiber in real time.

[0171] In some embodiments, when the braking pulse reaches a preset braking termination time, the computer control and processing unit sends a digital control command to the data acquisition card to force it to zero, so that the system enters a free decay state, that is, the residual energy is naturally dissipated by utilizing material internal friction and air damping.

[0172] In some embodiments, such as Figure 6 As shown, the energy efficiency difference between the "pulse-release" strategy proposed in this invention and the traditional continuous braking strategy is compared:

[0173] Under the same experimental conditions (system resonant frequency) Optimal braking phase Under the envelope function, two sets of comparative experiments were set up: the first set adopted the "pulse-release" strategy proposed in this invention, with a braking pulse width of... After selecting the optimal value (corresponding to several resonance cycles), it is forced to zero; the second group adopts the traditional continuous braking strategy, with a braking pulse width of... Extended several times, outputting braking signals throughout the entire range;

[0174] Experimental results show that the final braking times of the two schemes are basically the same, with differences within the measurement error range. However, the braking energy consumption of the "pulse-release" strategy is only a small proportion of that of the continuous braking strategy—because the system amplitude has dropped to the PSD noise floor level in the later stages of braking, and continuing to apply the braking signal has no substantial inhibitory effect. This confirms the core idea of ​​the "pulse-release" strategy: release the braking pulse immediately after the amplitude drops to the noise floor, relying on the system's internal friction to complete the final decay—ensuring braking speed while significantly saving energy.

[0175] In some embodiments, the superiority of the present invention over conventional 180° counter-phase braking in the 150°~210° range is illustrated from three independent physical mechanism systems:

[0176] Mechanism 1 (parameter robustness): Braking efficiency is determined by factors Modulation. In At 180°, It reaches a maximum value of 1, but its derivative... It is located at the extreme point of the envelope curve. When the phase fluctuates slightly due to temperature drift or frequency deviation, the 180° scheme only produces irreversible performance degradation. However, in the 150°~210° range, Within the linear segment of the envelope curve, phase error can be actively compensated through bidirectional adjustment. This applies at the boundary of the 150°~210° interval. The value is large enough (≥0.866), ensuring sufficient braking performance. For example... Figure 7 As shown, under the same braking pulse conditions, the amplitude envelope decay trajectory of the optimal phase of 150°~210° is significantly faster than that of the traditional 180° reverse phase braking.

[0177] Mechanism Two (Harmonic Pollution): When the waveforms of the braking and driving segments are joined at the splicing point, a 180° out-of-phase splicing inevitably introduces a signal abrupt change, equivalent to the superposition of square wave components. Fourier analysis shows that this square wave component contains odd harmonic components. A 150°~210° splicing maintains the continuity of the sinusoidal waveforms of the driving and braking segments, meaning there are no jumps at the splicing point, the spectrum is pure, and all braking energy is concentrated in the fundamental frequency mode. For example... Figure 8 As shown, the spectral comparison clearly reveals the differences between the two schemes: the 150°~210° scheme only differs in the fundamental frequency. There is a spectral line at that point, while the 180° scheme has... , The appearance of significant odd harmonic peaks verifies the physical mechanism by which square wave components are introduced to excite higher-order modes through 180° splicing.

[0178] Mechanism 3 (Zero Crossing Smoothness): The zero crossing point of the envelope corresponding to the 150°~210° interval is smoother, providing a safer cutoff window for the start and end of the braking pulse, reducing the risk of secondary excitation caused by cutoff timing deviation.

[0179] In summary, this invention expands the braking phase from the traditional fixed value of 180° to an optimizable range of 150°~210°, and combines a systematic screening of ten envelope functions with a "pulse-release" strategy to construct a complete, efficient, and robust piezoelectric fiber optic scanner cooperative braking technology solution.

[0180] This invention also provides a computer-readable storage medium storing a computer program. When executed by a processor, this computer program implements the various processes of the above-described embodiment of the coordinated braking method for a nonlinear microscopic imaging fiber optic scanner, achieving the same technical effect. The computer-readable storage medium can be of various types, such as read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0181] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for coordinated braking of a nonlinear microscopic imaging fiber optic scanner, characterized in that, Includes the following steps: Obtain the X-axis correction angle and the Y-axis correction angle, and based on the X-axis correction angle and the Y-axis correction angle, construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system to obtain the coordinate transformation relationship after error compensation; Obtain the system resonant frequency and quality factor, and determine the range of braking pulse width based on the system resonant frequency and the quality factor; Obtain the range of the phase interval, wherein the range of the phase interval is 150°~210°; With the braking pulse width fixed, a phase scanning experiment is performed using the braking phase as the scanning variable to determine the optimal braking phase, wherein the optimal braking phase is within the phase interval. The optimal envelope function is determined based on the system resonant frequency, the quality factor, the optimal braking phase, and the preset candidate envelope functions. At the termination time of the helical scan, a braking waveform is generated based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width. When the braking pulse reaches the preset braking moment, the braking signal is forced to zero, allowing the system to enter a free decay state.

2. The cooperative braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The acquisition of the X-axis correction angle and Y-axis correction angle includes: Single-axis response data for the X-axis and single-axis response data for the Y-axis are collected separately to obtain X-axis data and Y-axis data respectively; Ellipse least squares fitting is performed on the X-axis data and the Y-axis data respectively to obtain the X-axis fitted ellipse parameters and the Y-axis fitted ellipse parameters respectively. Based on the X-axis fitted ellipse parameters and the Y-axis fitted ellipse parameters, the X-axis correction angle and the Y-axis correction angle are obtained.

3. The cooperative braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system, based on the X-axis correction angle and the Y-axis correction angle, to obtain the coordinate transformation relationship after error compensation includes: The coordinate transformation relationship after error compensation is expressed by the following formula: in, For X-axis correction angle, For the Y-axis correction angle, These are the coordinate parameters before X-axis correction. These are the coordinate parameters after X-axis correction. These are the coordinate parameters before Y-axis correction. These are the Y-axis corrected coordinate parameters.

4. The cooperative braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The acquisition of the system resonant frequency and quality factor includes: A frequency sweep experiment was conducted within the preset resonant frequency range to obtain steady-state amplitude data at each frequency point, thereby obtaining amplitude-frequency data. Lorentzian fitting was performed on the amplitude-frequency data to obtain the system resonant frequency and full width at half maximum (FWHM) parameter; Based on the system resonant frequency and the full width at half maximum (FWHM) parameter, the first quality factor to be tested is obtained; Based on the system's resonant frequency, the second quality factor to be tested is obtained using the attenuation method. The first quality factor and the second quality factor to be tested are cross-validated to obtain the quality factor.

5. The coordinated braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The range of the obtained phase interval includes: Obtain permissible braking performance parameters; Obtain the braking efficiency and sensitivity values ​​corresponding to each phase; Based on the braking efficiency value and sensitivity value corresponding to each phase, the upper and lower boundaries of the phase interval are determined to obtain the range of the phase interval.

6. The coordinated braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The fixed braking pulse width, using the braking phase as the scanning variable, is used in a phase scanning experiment to determine the optimal braking phase, including: Under the condition of fixing the system resonant frequency, driving amplitude and braking pulse width, the braking phase is used as the scanning variable to traverse the range from 0° to 360°; Obtain the main evaluation index value and auxiliary verification index value for each phase; The phase corresponding to the smallest main evaluation index value is selected as the optimal braking phase.

7. The cooperative braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, The preset candidate envelope functions include power-law decay, exponential decay, S-curve, smooth S-curve, parabolic decay, inverse parabolic decay, step decay, oscillatory decay, logarithmic decay, and linear decay.

8. The cooperative braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 7, characterized in that, The determination of the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions includes: Under the condition of fixing the optimal braking phase and the braking pulse width, the preset candidate envelope functions are tested respectively, and a sorting table of the main evaluation index values ​​corresponding to each candidate envelope function is obtained. The optimal envelope function is determined based on the system resonant frequency, the quality factor, and the ranking table of the main evaluation index values ​​corresponding to each candidate envelope function.

9. The coordinated braking method for a nonlinear microscopic imaging fiber optic scanner according to claim 1, characterized in that, At the termination time of the helical scan, based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width, a braking waveform is generated, including: The braking waveform is represented by the following formula: ， in, This is the braking waveform. This is the braking amplitude. For the optimal envelope function, For the optimal braking phase, The system resonant frequency, The time when the helical scan terminates. This represents the braking pulse width.

10. A cooperative braking system for a nonlinear microscopic imaging fiber optic scanner, used to execute the cooperative braking method for the nonlinear microscopic imaging fiber optic scanner according to any one of claims 1 to 9, characterized in that, The system includes a computer control and processing unit, a data acquisition card, a drive execution unit, and a position-sensitive detector. The data acquisition card is connected to the computer control and processing unit and is used to acquire single-axis response data of the X-axis and single-axis response data of the Y-axis, as well as intermediate data in the cooperative braking method, according to the digital control instructions issued by the computer control and processing unit, and feed them back to the computer control and processing unit. The drive execution unit is connected to the analog output channel of the data acquisition card and is used to execute corresponding operations according to the analog instructions output by the analog output channel of the data acquisition card; The position-sensitive detector is connected to the data acquisition card and is used to send three photocurrent signals to the analog input channel of the data acquisition card; The computer control and processing unit includes an error compensation module, a system parameter determination module, an optimal braking determination module, an envelope function filtering module, a braking waveform generation module, and a zeroing control module. The error compensation module is used to obtain the X-axis correction angle and the Y-axis correction angle, and based on the X-axis correction angle and the Y-axis correction angle, to construct an asymmetric rotation transformation from the virtual driving coordinate system to the actual physical coordinate system, and obtain the coordinate transformation relationship after error compensation. The system parameter determination module is used to obtain the system resonant frequency and quality factor, and based on the system resonant frequency and quality factor, to determine the range of braking pulse width. The optimal braking determination module is used to obtain the range of the phase interval, fix the braking pulse width, and perform a phase scanning experiment with the braking phase as the scanning variable to determine the optimal braking phase; The envelope function filtering module is used to determine the optimal envelope function based on the system resonant frequency, quality factor, optimal braking phase, and preset candidate envelope functions. The braking waveform generation module is used to send braking control commands to the digital acquisition card at the end of the helical scan, and generate a braking waveform based on the coordinate transformation relationship after error compensation, the system resonant frequency, the optimal braking phase, the optimal envelope function, the optimal braking phase, and the braking pulse width. The zero-reset control module is used to force the braking signal to zero when the braking pulse reaches the preset braking moment, and to reset the digital control command sent to the data acquisition card to zero, so that the system enters the free decay state.

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