F-p etalon cavity length actuation correction method and correction device

Abstract

The application discloses a kind of F-P etalon cavity length actuation correction method and correction device, with the Preisach inverse model of path memory characteristic is applied to the cavity length actuation correction of F-P etalon, device passes through real-time tracking piezoelectric ceramic actuator's historical extreme value, it is solved and can offset nonlinear effect's drive voltage is exported;At the same time, with FPGA as execution carrier, it guarantees the nanosecond level output of this compensation model, the present application is with the Preisach inverse model to the feedforward compensation of F-P etalon cavity length actuation as core, supplemented by the hardware execution advantage of FPGA, the error generated by hysteresis nonlinear effect is compensated, and the cavity length regulation precision of F-P etalon is improved.

Description

Technical Field

[0001] This invention belongs to the field of optical resonator technology, specifically relating to a method and device for actuating and correcting the cavity length of an FP etalon. Background Technology

[0002] The Fabry-Perot etalon (FP etalon) is a high-resolution optical resonant cavity based on the principle of multi-beam interference. Its core structure consists of two parallel optical plates, each with a highly reflective dielectric film coated on its inner surface. When incident light enters the "resonant cavity" between these two plates, the light wave undergoes multiple reflections and transmissions within the cavity. Only light waves that meet specific phase resonance conditions can undergo constructive interference and be successfully transmitted. This physical characteristic makes the FP etalon macroscopically behave as a narrow-band optical filter, enabling precise wavelength extraction from complex broadband spectra.

[0003] FP etalons can be designed as dynamically tunable structures, and the core parameters for adjustment and control are "cavity length" and "parallelism". According to the principle of interference, by controlling the precise expansion and contraction of the cavity length, continuous dynamic scanning or precise locking of a specific wavelength spectrum can be achieved. However, the realization of this tuning characteristic has a stringent prerequisite: the displacement of the actual cavity length must maintain a highly linear mapping with the control command of the control system, and the cavity length adjustment accuracy must reach the sub-nanometer level.

[0004] In actual operation, piezoelectric ceramic actuators that drive changes in cavity length exhibit inherent hysteresis nonlinearity. During continuous dynamic scanning or precise locking, the lack of precise correction and compensation for these hysteresis nonlinearities causes the actual cavity length changes to deviate from the control commands. These hysteresis nonlinearities lead to nonlinear drift in the target transmission wavelength and distortion of the spectral scanning curve, ultimately causing the optical device to lose its high-precision spectral measurement and accurate filtering capabilities.

[0005] FP etalons typically use piezoelectric ceramics (PZT) as actuators to achieve precise sub-nanometer adjustment of the parallelism between the cavity length and the optical plate. However, piezoelectric ceramic actuators exhibit inherent hysteresis nonlinearity during actual operation, primarily manifested as a hysteresis effect. This hysteresis nonlinearity means that the actuator's output displacement depends not only on the current driving voltage but also heavily on the historical rise and fall paths of the driving voltage, resulting in the boost and buck curves not coinciding. The hysteresis nonlinearity fundamentally disrupts the ideal linear mapping relationship between the driving voltage and the actual displacement, representing a core technological bottleneck restricting the system from achieving high-frequency precise positioning.

[0006] To overcome the hysteresis nonlinearity of piezoelectric ceramics, existing systems often resort to simple linear approximations or rely entirely on sensors to detect actual displacement deviations before implementing passive closed-loop error feedback compensation. This "hysteresis" not only fails to meet the requirements of high-speed dynamic scanning in optical systems but also easily induces oscillations when approaching the target cavity length. The application of high-precision hysteresis physical models in FP etalon control has long been lacking. Although in the field of electromechanical drives, models such as the Preisach inverse model are known to accurately describe the electrical / magnetic hysteresis characteristics of materials, traditional FP etalon control systems have not systematically incorporated such complex high-order models into their cavity length actuation correction.

[0007] Therefore, how to break through the limitations of the traditional passive control architecture of optical cavities, apply the Preisach inverse model to the cavity length actuation correction of FP etalons, construct a set of feedforward compensation logic for cavity length actuation of FP etalons, and meet the real-time requirements of optical control, supplemented by underlying logic hardware (such as FPGA) as the execution carrier to ensure the implementation of the model, so as to realize the nonlinear error correction of FP etalons during actuation, is a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0008] The purpose of this invention is to solve the problem that in the prior art, when performing large-range wavelength scanning or micro-step adjustment, a significant nonlinear deviation occurs between the actual cavity length and the driving voltage, which affects the positioning accuracy and repeatability of spectral scanning. Therefore, this invention proposes to apply the Preisach inverse model with path memory characteristics to the cavity length actuation correction of FP etalons, and provides a method and device for FP etalon cavity length actuation correction.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0010] A method for correcting the cavity length actuation of a standard FP terephthalic device includes the following steps:

[0011] Step 1: Reading the expected cavity length change

[0012] At the start of the sampling period, the digital control and nonlinear compensation module reads the expected cavity length change from the coordinate matrix decoupling calculation output, which is the ideal target displacement that the optical plate of the FP etalon needs to achieve in the current period.

[0013] Step 2: Determining the Movement Trend

[0014] The digital control and nonlinear correction compensation module built into the FPGA uses the Preisach inverse model feedforward compensation algorithm to compare the expected cavity length change in the current cycle with the expected cavity length command value in the previous sampling cycle, and distinguish the current motion trend of the piezoelectric ceramic actuator, that is, to distinguish whether the current FP etalon is in a "cavity length increase" or "cavity length decrease" trend.

[0015] Step 3: Extreme value determination and memory update

[0016] The Preisach inverse model feedforward compensation algorithm monitors the input trajectory and determines whether a new input extremum has been generated (i.e. whether the direction of motion has been reversed).

[0017] If the determination is yes, the device executes the Wiping-out mechanism of the Preisach inverse model, that is, deletes invalid extreme values ​​covered by the current extreme value in the historical extreme value sequence, and pushes the new input extreme value into the historical extreme value stack to update the model memory state; this mechanism effectively avoids memory redundancy and ensures the path accuracy under complex non-monotonic scans; if the determination is no, the current extreme value stack state remains unchanged.

[0018] Step 4: Determine the state boundary

[0019] Regardless of whether the extreme value stack is updated, the algorithm executes sequentially downwards, determining the state boundary of the current Preisach inverse model based on the historical extreme value sequence recorded in the historical extreme value stack.

[0020] Step 5: Inverse Model Solution and Voltage Reconstruction

[0021] Step 5 is the core of the Preisach inverse model feedforward compensation algorithm. The algorithm performs inverse mapping calculation from the ideal target displacement to the driving voltage based on the current expected cavity length change, the state boundary determined in step 4, and the weight function pre-stored in the device. Through this inverse mapping calculation, the algorithm calculates the driving voltage that can correct the hysteresis nonlinear error.

[0022] Step 6: Instruction Issuance and Looping

[0023] The device sends the driving voltage, which can correct the hysteresis nonlinearity error, as a control command to the digital-to-analog converter (DAC). The piezoelectric ceramic actuator generates a corresponding displacement under the action of the driving voltage, thereby realizing the correction and compensation of the hysteresis nonlinearity effect of the piezoelectric ceramic actuator. Subsequently, the algorithm enters a waiting state until the next sampling period arrives and steps 1 to 6 are triggered again, thereby realizing the dynamic correction of the FP standard etalon cavity length actuation.

[0024] A correction device for a piezoelectric etalon cavity length actuation correction method includes: a multi-channel microcapacitive sensing signal conditioning and acquisition module, a command interaction and status monitoring module, a digital control and nonlinear correction compensation module, a piezoelectric drive module, and a piezoelectric etalon assembly.

[0025] The control closed loop of the device begins with the FP etalon assembly. Multi-channel micro-capacitive sensing probes, orthogonally arranged along three axes on the FP etalon, can measure the gap changes between optical plates in real time and output a weak analog capacitance signal. This analog capacitance signal enters the signal conditioning and acquisition module, where it first undergoes high-sensitivity capacitance-to-voltage (CV) conversion, low-noise amplification, and impedance matching via analog signal conditioning and amplification circuits, converting the analog capacitance change into an analog voltage signal. This analog voltage signal then enters a high-precision ADC (analog-to-digital converter), synchronously converting the continuous analog voltage signal into a discrete digital signal. The discrete digital signal is then uploaded to the subsequent digital control and nonlinear correction compensation module via a data transmission interface.

[0026] The command interaction and status monitoring module is typically deployed on the host computer. The command interaction unit is responsible for receiving the user's control intentions, where the user can set the target cavity length and the X-axis parallelism error threshold. Y-axis parallelism error threshold and Z-axis cavity length error threshold The user-defined target cavity length is parsed into a digital signal as a reference command. At the same time, the module receives the current cavity length position, X-axis tilt, and Y-axis tilt data from the underlying hardware in real time through bidirectional communication, which is used for real-time monitoring of the device status on the display unit.

[0027] The digital control and nonlinear correction compensation module relies on a high-performance digital processing platform to achieve underlying hardware-based computation. The FPGA first performs digital filtering on the acquired discrete digital signal; then, using the pre-calibrated sensing coefficients of the device, it linearly converts the filtered discrete digital signal into the current actual displacement (gap) of the FPGA etalon; it calculates the error between the user-set target cavity length (which is not digitally filtered) and the converted actual displacement, and generates an error quantity in real time that includes the current cavity length deviation and parallelism deviation.

[0028] The generated error enters the PID closed-loop control unit, where the PID algorithm calculates the desired displacement compensation (i.e., thrust command) required to counteract the dynamic disturbance based on the current error. Subsequently, the desired displacement compensation enters the coordinate matrix decoupling unit. Since the FP etalon adopts a structure of multi-channel capacitive sensing probes arranged in orthogonal triaxial configuration and piezoelectric ceramic actuators (A, B, C) evenly distributed at three points, the coordinate matrix decoupling unit performs spatial coordinate transformation through the built-in decoupling matrix, mapping the desired displacement compensation into the independent desired displacement (desired cavity length change) required to drive each of the three piezoelectric ceramic actuators.

[0029] To overcome the hysteresis nonlinear effect of piezoelectric ceramic materials, the Preisach inverse model feedforward compensation algorithm built into the digital control and nonlinear correction compensation module receives the desired cavity length change and performs feedforward inverse calculation, outputting control commands.

[0030] The control command, after nonlinear correction and compensation, is sent to the piezoelectric drive module. The control command first enters the module through the drive logic interface; it is then converted into an analog control voltage by the digital-to-analog converter; this analog control voltage finally enters the high-voltage amplifier and is amplified to the drive voltage required to drive the piezoelectric ceramic actuator (e.g., 0V-900V), thereby driving the three piezoelectric ceramic actuators (A, B, C) in the FP etalon assembly.

[0031] The FP etalon assembly is the controlled object of the device, consisting of three piezoelectric ceramic actuators (A, B, C) evenly distributed at three points, and a multi-channel micro-capacitive sensing probe arranged orthogonally along three axes to measure the capacitance values ​​of six channels. Driven by the driving voltage, the piezoelectric ceramic actuator produces nanometer-level precision expansion and contraction, pushing the optical plate of the FP etalon, changing its cavity length and correcting the parallelism of the optical plate, thereby achieving precise control of optical properties.

[0032] Compared with existing technologies, the present invention has the following beneficial technical effects:

[0033] 1. This invention innovatively embeds a high-precision Preisach inverse model feedforward compensation algorithm into the digital control and nonlinear correction compensation module. This model performs feedforward compensation by tracking the historical extreme values ​​and erasure characteristics of the control command in real time, and outputs a driving voltage that can correct hysteresis nonlinear error, thereby realizing a linear relationship between the control command and the actual optical cavity length change, thus improving the cavity length adjustment accuracy of the FP standard etalon.

[0034] 2. This invention applies the Preisach inverse model feedforward compensation algorithm with path memory characteristics to the cavity length actuation correction of the FP etalon. By tracking the historical extreme values ​​of the control commands of the piezoelectric ceramic actuator in real time, it calculates and outputs a driving voltage that can offset the nonlinear characteristics.

[0035] 3. This invention uses FPGA (Field Programmable Gate Array) as the execution carrier, which ensures the nanosecond-level output of the model, realizes the correction and compensation of hysteresis nonlinear error, and improves the cavity length adjustment accuracy of FPGA standard etalon. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the FP etalon assembly in an embodiment of the FP etalon cavity length actuation correction device of the present invention.

[0037] Figure 2 This is a schematic diagram of the structural principle of an embodiment of the FP standard etalon length actuation correction device of the present invention.

[0038] Figure 3 This is a flowchart illustrating the execution of a Preisach inverse model feedforward compensation algorithm based on an embodiment of a method for correcting the cavity length of a FP standard tether according to the present invention. Detailed Implementation

[0039] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0040] FP etalon components are the controlled objects of the device; see [link / reference]. Figure 1 It includes three piezoelectric ceramic actuators (A, B, C) evenly distributed at three points, and a multi-channel micro-capacitive sensing probe arranged orthogonally along three axes. The multi-channel micro-capacitive sensing probe is used to measure the capacitance values ​​of six channels. Driven by the driving voltage, the piezoelectric ceramic actuator produces nanometer-level precision expansion and contraction, pushing the optical plate of the FP etalon, changing its cavity length and correcting the parallelism of the optical plate, thereby achieving precise control of optical properties.

[0041] like Figure 2 As shown, the correction device for implementing the FP etalon cavity length actuation correction method includes: a multi-channel microcapacitor signal conditioning and acquisition module, a command interaction and status monitoring module, a digital control and nonlinear correction compensation module, a piezoelectric drive module, and an FP etalon assembly.

[0042] The control closed loop of the correction device begins with the FP etalon assembly. The multi-channel micro-capacitive sensing probes arranged orthogonally on the FP etalon assembly can measure the gap change between the two optical plates in real time and output a weak analog capacitance signal. This analog capacitance signal enters the multi-channel micro-capacitive signal conditioning and acquisition module, where it first undergoes high-sensitivity capacitance-to-voltage (CV) conversion, low-noise amplification, and impedance matching through analog signal conditioning and amplification circuits, converting the analog capacitance signal into an analog voltage signal. This analog voltage signal then enters the high-precision ADC (analog-to-digital converter), which synchronously converts the continuous analog voltage signal into a discrete digital signal. The discrete digital signal is then uploaded to the subsequent digital control and nonlinear correction compensation module through the data transmission interface.

[0043] The command interaction and status monitoring module is typically deployed on the host computer. The command interaction unit is responsible for receiving user control commands, where users can set search parameters and X-axis parallelism error thresholds. Y-axis parallelism error threshold and Z-axis cavity length error threshold The user-defined target cavity length is parsed into a digital signal as a reference command. At the same time, the module receives the current cavity length position, X-axis tilt, and Y-axis tilt data from the underlying hardware in real time through bidirectional communication, which is used for real-time monitoring of the device status on the display unit.

[0044] The digital control and nonlinear correction compensation module relies on FPGA for underlying hardware computation. The FPGA first performs digital filtering on the acquired discrete digital signal; then, using the pre-calibrated sensing coefficients of the device, it linearly converts the filtered discrete digital signal into the current actual displacement (gap) of the FPGA etalon; it calculates the error between the user-set target cavity length (which is not digitally filtered) and the converted actual displacement, and generates an error quantity in real time that includes the current cavity length deviation and parallelism deviation.

[0045] The generated error quantity enters the PID closed-loop control unit, where the PID algorithm calculates the desired displacement compensation amount (i.e., thrust command) required by the device to counteract dynamic disturbances based on the current error quantity. Subsequently, the desired displacement compensation amount enters the coordinate matrix decoupling unit. Since the FP etalon assembly adopts a structure of multi-channel capacitive sensing probes arranged in orthogonal triaxial directions and piezoelectric ceramic actuators (A, B, C) evenly distributed at three points, the coordinate matrix decoupling unit performs spatial coordinate transformation through the built-in decoupling matrix, mapping the desired displacement compensation amount into the independent desired displacement amount (desired cavity length change amount) required to drive each of the three piezoelectric ceramic actuators.

[0046] To overcome the hysteresis nonlinear effect of piezoelectric ceramic materials, the Preisach inverse model feedforward compensation algorithm built into the digital control and nonlinear correction compensation module receives the desired cavity length change and performs feedforward compensation, outputting control commands including the driving voltage.

[0047] The control command, after nonlinear correction and compensation, is sent to the piezoelectric drive module. The control command first enters the module through the drive logic interface; it is then converted into an analog control voltage by the digital-to-analog converter; this analog control voltage finally enters the high-voltage amplifier and is amplified to the drive voltage required to drive the piezoelectric ceramic actuator (e.g., 0V-900V), thereby driving the three piezoelectric ceramic actuators (A, B, C) in the FP etalon assembly.

[0048] like Figure 3 As shown, this embodiment provides a method for correcting the cavity length of a standard FP tee, including the following steps:

[0049] Step 1: Reading the expected cavity length change

[0050] At the start of the sampling period, the digital control and nonlinear correction compensation module built into the FPGA reads the expected cavity length change from the coordinate matrix decoupling calculation output, which is the ideal target displacement that the FP etalon optical plate needs to achieve in the current period.

[0051] Step 2: Determining the Movement Trend

[0052] The Preisach inverse model feedforward compensation algorithm in the digital control and nonlinear correction compensation module built into the FPGA compares the expected cavity length change in the current cycle with the control command in the previous sampling cycle to determine the current motion trend of the piezoelectric ceramic actuator, that is, to distinguish whether the current FP etalon is in a "cavity length increase" or "cavity length decrease" trend.

[0053] Step 3: Extreme value determination and memory update

[0054] The Preisach inverse model feedforward compensation algorithm monitors the input trajectory and determines whether a new input extremum has been generated (i.e. whether the direction of motion has been reversed).

[0055] If the determination is yes, the wipe-out mechanism unique to the Preisach inverse model is executed, that is, invalid extreme values ​​covered by the current extreme value are deleted from the historical extreme value sequence, and the new input extreme value is pushed into the historical extreme value stack to update the model memory state; this mechanism effectively avoids memory redundancy and ensures the path accuracy under complex non-monotonic scans; if the determination is no, the current extreme value stack state remains unchanged.

[0056] Step 4: Determine the state boundary

[0057] Regardless of whether the extreme value stack is updated, the algorithm executes sequentially downwards, determining the state boundary of the Preisach inverse model based on the historical extreme value sequence recorded in the historical extreme value stack.

[0058] Step 5: Inverse Model Solution and Voltage Reconstruction

[0059] This step is the core of the Preisach inverse model feedforward compensation algorithm. The algorithm calculates the inverse mapping from the ideal target displacement to the driving voltage based on the current expected cavity length change, the state boundary determined in step 4, and the weight function stored in the device; thus obtaining the driving voltage that can correct the hysteresis nonlinear error.

[0060] Step 6: Instruction Issuance and Looping

[0061] The driving voltage, which can correct the hysteresis nonlinearity error, is sent as a control command to the digital-to-analog converter (DAC). The piezoelectric ceramic actuator generates a corresponding displacement under the action of the driving voltage, thereby correcting the hysteresis nonlinearity effect of the piezoelectric ceramic actuator. Subsequently, the algorithm enters a waiting state until the next sampling period arrives, when steps 1 to 6 are triggered again, thereby realizing the dynamic correction of the FP standard etalon cavity length actuation.

[0062] Although this invention uses the cavity length actuation correction of the FP etalon as an example for detailed description, those skilled in the art should understand that the core essence of the feedforward compensation architecture based on the Preisach inverse model and real-time tracking of historical extreme values ​​proposed in this invention is to solve the displacement deviation problem caused by the hysteresis nonlinearity effect of piezoelectric ceramic actuators. Therefore, the method and device of this invention are also applicable to any optomechanical system that relies on piezoelectric ceramic actuators for precise positioning, such as atomic force microscope scanning stages, adaptive optics deformable mirrors, and micro-nano lithography positioning platforms. Furthermore, although the embodiments of this invention preferably use the Preisach inverse model, other hysteresis models with path memory characteristics (such as the Prandtl-Ishlinskii model, Bouc-Wen model, etc.) can be used to replace the Preisach inverse model of this invention, or a simplified static lookup table method with equivalent logic can be used. At the implementation level, the inverse mapping calculation is preferably performed on an FPGA, but it can also be implemented by other hardware platforms with parallel or high-speed computing capabilities, such as digital signal processors (DSPs), embedded ARM microprocessors, etc. All equivalent replacements, improvements, or extensions that employ feedforward reverse calculations and combine them with hardware implementations to meet real-time control requirements should be included within the scope of protection of this invention.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A method for correcting the cavity length of a standard FP device, characterized in that, Includes the following steps: Step 1: Reading the expected cavity length change At the start of the sampling period, the digital control and nonlinear correction compensation module reads the expected cavity length change from the coordinate matrix decoupling calculation output, which is the ideal target displacement that the optical plate of the FP etalon needs to achieve in the current period. Step 2: Determining the Movement Trend The digital control and nonlinear correction compensation module built into the FPGA uses the Preisach inverse model feedforward compensation algorithm to compare the expected cavity length change in the current cycle with the expected cavity length command value in the previous sampling cycle, and distinguish the current movement trend of the piezoelectric ceramic actuator, that is, to distinguish whether the current FP etalon is in a "cavity length increase" or "cavity length decrease" trend. Step 3: Extreme Value Determination and Memory Update The Preisach inverse model feedforward compensation algorithm monitors the input trajectory and determines whether a new input extremum has been generated, i.e., whether the direction of motion has reversed. If the determination is yes, the device executes the erasure characteristic mechanism of the Preisach inverse model, i.e., deletes the invalid extremum covered by the current extremum in the historical extremum sequence, and pushes the new input extremum into the historical extremum stack to update the model memory state. If the determination is no, the current extremum stack state remains unchanged. Step 4: Determine the state boundary Regardless of whether the extreme value stack is updated, the algorithm executes sequentially downwards, determining the state boundary of the Preisach inverse model based on the historical extreme value sequence recorded in the current historical extreme value stack. Step 5: Inverse Model Solution and Voltage Reconstruction The algorithm performs an inverse mapping calculation from the ideal target displacement to the driving voltage based on the current expected cavity length change, the state boundary determined in step 4, and the weight function pre-stored in the device. Through this inverse mapping calculation, the algorithm calculates the driving voltage that can correct for hysteresis nonlinearity errors. Step 6: Instruction Issuance and Looping The device sends the driving voltage, which can correct the hysteresis nonlinearity error, to the digital-to-analog converter as a control command. The piezoelectric ceramic actuator generates a corresponding displacement under the action of the driving voltage, thereby correcting and compensating for the hysteresis nonlinearity effect of the piezoelectric ceramic actuator. When the next sampling period arrives, the algorithm triggers steps 1 to 6 again to achieve dynamic correction of the FP standard etalon cavity length actuation.

2. A correction apparatus for implementing the FP standard etalon length actuation correction method according to claim 1, comprising: The multi-channel micro-capacitive sensing signal conditioning and acquisition module, command interaction and status monitoring module, digital control and nonlinear correction and compensation module, piezoelectric drive module, and FP etalon assembly are characterized by: The control closed loop of the device begins with the FP etalon assembly. A multi-channel micro-capacitive sensing probe, orthogonally arranged along three axes on the FP etalon, can measure the gap change between optical plates in real time and output a capacitance sensing analog signal. This capacitance sensing analog signal enters the multi-channel micro-capacitive sensing signal conditioning and acquisition module. First, it undergoes high-sensitivity capacitance-to-voltage conversion, low-noise amplification, and impedance matching via analog signal conditioning and amplification circuitry, converting the analog capacitance change into an analog voltage signal. This analog voltage signal then enters the analog-to-digital converter, synchronously converting the continuous analog voltage signal into a discrete digital signal. Finally, the discrete digital signal is uploaded to the subsequent digital control and nonlinear correction compensation module via a data transmission interface. The digital control and nonlinear correction and compensation module relies on the high-performance digital processing platform FPGA to realize the underlying hardware operation. The FPGA performs digital filtering on the acquired multi-channel micro-capacitive sensing signals. Then, using the sensing coefficients pre-calibrated by the device, the filtered voltage signal is linearly converted into the current gap of the FP etalon, i.e., the displacement. The error is calculated between the user-set target cavity length command of the unfiltered wave circuit and the converted actual displacement, and an error quantity containing the current cavity length deviation and parallelism deviation is generated in real time. The generated error enters the PID closed-loop control unit, where the PID algorithm calculates the desired displacement compensation amount required to offset the dynamic disturbance based on the current error. Subsequently, the desired displacement compensation amount enters the coordinate matrix decoupling unit. Since the FP etalon adopts a multi-channel micro-capacitive sensing probe arranged in orthogonal triaxial and a piezoelectric ceramic actuator structure with three points evenly distributed, the spatial coordinate transformation is performed through the built-in decoupling matrix to map the desired displacement compensation amount into the independent desired displacement amount required to drive each of the three piezoelectric ceramic actuators, i.e., the desired cavity length change amount. The control command, after nonlinear correction and compensation, is sent to the piezoelectric drive module and enters the piezoelectric drive module through the drive logic interface. It is then converted into an analog control voltage by the digital-to-analog converter. The analog control voltage is amplified by the high-voltage amplifier to the drive voltage required to drive the piezoelectric ceramic actuators, thereby driving the three piezoelectric ceramic actuators in the FP etalon assembly.

3. The correction device according to claim 2, characterized in that: The command interaction and status monitoring module is deployed on the host computer. The command interaction unit is responsible for receiving the user's control intentions. The user can set the target cavity length and the X-axis parallelism error threshold here. Y-axis parallelism error threshold and Z-axis cavity length error threshold The user-defined target cavity length is parsed into a digital signal as a reference command. At the same time, the command interaction and status monitoring module receives the current cavity length position, X-axis tilt, and Y-axis tilt data from the underlying hardware in real time through bidirectional communication, which is used to monitor the device status in real time on the display unit.

4. The correction device according to claim 2, characterized in that: To overcome the hysteresis nonlinear effect of piezoelectric ceramic materials, the Preisach inverse model feedforward compensation algorithm built into the digital control and nonlinear correction compensation module receives the desired cavity length change and performs feedforward inverse calculation, outputting control commands.

5. The correction device according to claim 2, characterized in that: The FP etalon assembly is the controlled object of the device, consisting of three piezoelectric ceramic actuators evenly distributed at three points and a multi-channel micro-capacitive sensing probe arranged orthogonally along three axes to measure the capacitance values ​​of six channels. ; Driven by a driving voltage, the piezoelectric ceramic actuator produces nanometer-level precision expansion and contraction, pushing the optical plate of the FP etalon, changing its cavity length and correcting the parallelism of the optical plate, thereby achieving precise control of optical properties.

6. The correction device according to claim 2, characterized in that: The driving voltage required to drive the piezoelectric ceramic actuator is 0V-900V.

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