A moving mirror scanning device for a high-resolution Fourier transform spectrometer

Abstract

This invention discloses a moving mirror scanning device for a high-resolution Fourier transform spectrometer, relating to the field of optical interferometry technology. The moving mirror scanning device for a high-resolution Fourier transform spectrometer includes a moving mirror scanning unit with a corner reflector at the moving mirror end, and a two-stage drive module consisting of a power component and a voice coil motor. The position detection module includes a photoelectric switch for limit positioning and a laser interferometer system for real-time feedback. The control module coordinates the primary drive for basic scanning and, based on the deviation calculated in real-time from the laser interferometer signal, adjusts the output of the voice coil motor in a closed-loop manner. This invention achieves long-stroke precision scanning through two-stage coordinated drive. The power component provides main traction, and the voice coil motor performs real-time closed-loop fine-tuning based on the laser interferometer signal, overcoming the contradiction between speed and accuracy inherent in traditional single-drive methods. The spring steel spring sheet and precision guide structure effectively suppress lateral movement and vibration, ensuring the straightness of the motion trajectory.

Description

Technical Field

[0001] This invention relates to the field of optical interferometry technology, specifically to a moving mirror scanning device for a high-resolution Fourier transform spectrometer. Background Technology

[0002] Fourier transform spectrometers are based on the principle of Michelson interferometers. They measure the interference pattern generated by the interference of two beams of light during the movement of a moving mirror, and then use Fourier transform to recover the spectral information. The core indicator is spectral resolution, which directly depends on the maximum optical path difference of the moving mirror and the stability and linearity of the scanning process. Therefore, driving the moving mirror to perform high-speed, long-stroke, and high-precision uniform linear motion is the key to obtaining high-resolution spectra.

[0003] Currently, there are various technical solutions for achieving moving mirror scanning. For example, voice coil motors are used for direct drive to achieve fast response and accurate positioning, or linear motors, servo motors and ball screws are used to provide long-stroke motion. These technical solutions are all pursuing improvements in performance indicators such as scanning speed, stroke range and motion accuracy to meet the growing demand for spectral measurement performance in different application scenarios.

[0004] The limitations of existing technologies include at least the following problems: Existing moving mirror scanning devices often employ a single driving method, such as relying solely on a stepper motor for long-stroke traction or solely on a voice coil motor for short-stroke precision movement. This design makes it difficult to simultaneously meet the core requirements of large stroke and high precision during the long-distance, high-linearity scanning process required by Fourier transform spectrometers. Specifically, while stepper motor drives can achieve large-range movement, their dynamic response is slow, and they suffer from step vibration and transmission backlash, making it difficult to achieve high-smoothness uniform speed scanning. On the other hand, while voice coil motors have fast response and high control precision, their own stroke is limited. This fundamental contradiction results in insufficient speed stability during the scanning process, directly affecting the contrast and linearity of the interference fringe signal, thereby limiting the resolution and signal-to-noise ratio that the spectrometer can ultimately achieve. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a moving mirror scanning device for high-resolution Fourier transform spectrometers, which solves the problem that existing moving mirror scanning devices using a single driving method cannot simultaneously achieve high precision and high speed in long-stroke scanning.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a moving mirror scanning device for a high-resolution Fourier transform spectrometer, comprising: a moving mirror scanning device having a moving mirror end-angle reflector for reflecting the measurement beam; a dual-stage drive module having a power component for providing a first-stage stroke traction drive and a voice coil motor for providing a second-stage adjustment drive, the power component being connected to the moving mirror scanning device via a traction structure, and the voice coil motor mover being fixedly connected to the moving mirror scanning device; a position detection module having a front position lever and a rear position lever with photoelectric switches for detecting the stroke limit position of the moving mirror, and a laser interference feedback module for generating interference signals in real time, the laser interference feedback module including a laser, a beam splitter, a fixed mirror end-angle reflector, and a laser detector; and a control module electrically connected to the dual-stage drive module and the position detection module, configured to: control the power component to drive the moving mirror scanning device to perform scanning motion; calculate the motion state deviation based on the interference signal fed back by the laser detector; and adjust the drive output of the voice coil motor according to the deviation in a closed loop.

[0007] Furthermore, the moving mirror scanning device also includes an upper sliding bracket, a lower sliding bracket, and a moving mirror assembly base plate. The moving mirror end corner reflector is installed on the front end of the upper sliding bracket through the front assembly plate of the sliding bracket. The voice coil motor mover is installed on the rear end of the upper sliding bracket. The moving mirror assembly base plate is fixedly connected to the lower sliding bracket. The voice coil motor stator is positioned and fixed through the V-groove on the moving mirror assembly base plate.

[0008] Furthermore, spring steel spring sheets are installed between the four corners of the upper and lower sliding brackets to provide elastic support along the scanning axis.

[0009] Furthermore, it also includes an optical axis guide rail and multiple sliding bearings. The sliding bearings are installed at the bottom of the moving mirror assembly base plate and roll in cooperation with the optical axis guide rail to form a rolling guide pair.

[0010] Furthermore, the traction structure includes a pulley assembly containing bearings and a moving mirror steel wire rope. The power assembly pulls the moving mirror scanning device through the moving mirror steel wire rope and pulley assembly. The fixed mirror end angle reflector is equipped with a fixed mirror adjustment device.

[0011] Furthermore, the control module executes the moving mirror scanning control process as follows: The power component is controlled to move the moving mirror scanning device, causing the front position lever to trigger the pre-set zero-position photoelectric switch, setting the interference signal count value output by the laser detector to 0, thus completing the system zero-position calibration; a smooth speed planning trajectory is generated based on the target scanning speed and scanning length; the power component is controlled to drive the moving mirror scanning device to begin scanning motion along the optical axis guide rail, ensuring its speed follows the speed planning trajectory; during the scanning motion, the interference signal output by the laser detector is acquired and processed in real time to calculate the instantaneous actual speed of the moving mirror scanning device; the deviation between the instantaneous actual speed and the target speed of the speed planning trajectory is calculated; based on the deviation value and combined with the feedforward compensation amount calculated based on the difference between the target speed and the real-time speed, the drive current output to the voice coil motor mover is adjusted in real time to complete the closed-loop regulation of the scanning speed.

[0012] Furthermore, the specific steps for real-time acquisition and processing of the interference signal to calculate the instantaneous actual velocity are as follows: Analog-to-digital conversion and digital sampling are performed on the interference fringe signal output by the laser detector; the periodic zero-crossing points of the digital signal are identified, and fringe pulse counting is performed; the signal waveform within the current fringe period is analyzed in real time to obtain the real-time phase value within that period; based on the fringe pulse count and the real-time phase value, the real-time displacement of the moving mirror scanning device is calculated; the real-time displacement is differentiated to obtain the instantaneous actual velocity of the moving mirror scanning device.

[0013] Furthermore, the specific steps for calculating and generating the feedforward compensation amount are as follows: Based on the motion characteristics of the moving mirror scanning device, a feedforward control model is established; during the scanning process, the difference between the target speed and the current speed is calculated; the difference is input into the feedforward control model to calculate the theoretical compensation force; based on the force constant of the voice coil motor, the theoretical compensation force is converted into the corresponding feedforward current compensation amount.

[0014] Furthermore, the specific steps of the control module in executing the safety control at the scanning endpoint are as follows: During the scanning process, the real-time position and speed of the moving mirror scanning device are continuously compared with the target speed to calculate the speed deviation value; based on the deviation value and the feedforward compensation amount calculated based on the difference between the target speed and the real-time speed, the drive current output to the voice coil motor mover is adjusted in real time; when the deviation value is positive, an acceleration command is sent to the power component, and an active drive current in the same direction of movement is simultaneously output to the voice coil motor mover; when the deviation value is negative, a deceleration command is sent to the power component, and an active damping current in the opposite direction of movement is simultaneously output to the voice coil motor mover; when the deviation value is zero, the existing speed is maintained.

[0015] Furthermore, the specific steps for the control module to perform online calibration of system parameters are as follows: when the moving mirror scanning device is in a stable uniform scanning phase, a set of small sinusoidal test signals of a set frequency are superimposed on the driving current of the voice coil motor mover; the interference signal output by the laser detector is acquired synchronously, and the phase or velocity modulation component caused by the test signal is extracted; the amplitude ratio and velocity difference between the test signal and the system response signal are analyzed, and the equivalent mass in the feedforward control model is identified and updated.

[0016] The present invention has the following beneficial effects:

[0017] (1) The moving mirror scanning device for high-resolution Fourier transform spectrometer significantly improves the accuracy of scanning motion through the coordinated operation of the dual-stage drive module and the position detection module. The power component realizes the large-range stroke traction of the moving mirror scanning device through the traction structure, providing basic driving force for scanning. The voice coil motor is directly connected to the moving mirror scanning device and undertakes the real-time micro-adjustment function. The laser interference feedback module continuously generates interference signals. The control module calculates the motion deviation based on these signals, adjusts the drive output of the voice coil motor in a closed loop, and corrects the offset in the motion process in a timely manner. At the same time, the spring steel sheet between the upper sliding bracket and the lower sliding bracket provides axial elastic support. The rolling guide pair composed of the optical axis guide rail and the sliding bearing ensures the stability of the motion direction. The combination of multiple structures ensures that the moving mirror scanning process remains stable, providing a core guarantee for the spectrometer to achieve high-resolution detection.

[0018] (2) The moving mirror scanning device for high-resolution Fourier transform spectrometer first completes the zero-position calibration of the system to establish an accurate benchmark for scanning. Then, it generates a smooth speed planning trajectory based on the target to ensure natural motion connection. During the scanning process, interference signals are collected in real time and the instantaneous actual speed is calculated. The deviation is calculated after comparing with the target speed. The voice coil motor drive current is adjusted in combination with the feedforward compensation to effectively overcome various interference factors in the system operation. When the scanning is close to the end point, the braking command is triggered by the speed deviation value. The reverse active damping current is used to achieve smooth stopping and avoid collision damage. The system can also calibrate parameters online. The model parameters are identified and updated by superimposing test signals, so that the device can always maintain stable performance in long-term use and reduce maintenance costs.

[0019] (3) The moving mirror scanning device for high-resolution Fourier transform spectrometer adopts a combination structure of upper sliding bracket, lower sliding bracket and moving mirror assembly base plate. The voice coil motor stator is fixed by V groove positioning, which is firm and precise. Spring steel spring sheets are installed at the four corners of the bracket, which not only provides elastic support, but also helps to constrain the direction of movement. The distribution design of sliding bearings makes the device fit closely with the optical axis guide rail, and it is not easy to shake during movement. The traction structure adopts pulley assembly and steel wire rope cooperation, which makes the transmission smooth and easy to install. The fixed mirror adjustment device can flexibly adjust the attitude of the fixed mirror end angle reflector to optimize the interference effect. The components of the overall structure have clear division of labor and cooperate with each other, which not only ensures the stability of the optical path, but also makes the assembly and debugging of the device more convenient. It is suitable for the use of high-resolution infrared spectrometer and other high-precision interferometric measurement systems.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the moving mirror scanning device for a high-resolution Fourier transform spectrometer according to the present invention.

[0022] Figure 2 This is a front view structural diagram of the present invention.

[0023] Figure 3 This is a side view of the structure of the present invention.

[0024] Figure 4 This is a structural example diagram of the laser feedback system of the present invention and its application in a Michelson interferometer.

[0025] Figure 5 This is a schematic diagram showing the connection between the optical axis guide rail and the moving mirror scanning device in the case of the present invention used in a high-resolution Michelson interferometer.

[0026] Figure 6 This is a schematic diagram of the power component structure of the present invention.

[0027] Figure 7 This is a flowchart illustrating the specific steps involved in real-time acquisition and processing of interference signals to calculate instantaneous actual velocity in a moving mirror scanning device for a high-resolution Fourier transform spectrometer.

[0028] In the diagram: 1. Moving mirror end corner reflector; 2. Front position lever; 3. Front assembly plate of sliding bracket; 4. Rubber buffer pad; 5. Mounting plate that can be used with a grating ruler; 6. Upper sliding bracket; 7. Voice coil motor stator; 8. Voice coil motor mover; 9. Rear position lever; 10. Rear assembly plate of sliding bracket; 11. Spring steel pressure block; 12. Spring steel spring sheet; 13. Spring sheet pressure block; 14. Lower sliding bracket; 15. Sliding bearing; 16. Moving mirror assembly base plate; 17. Guide rod; 100. Moving mirror scanning device; 101. Beam splitter; 102. Fixed mirror end corner reflector; 103. Fixed mirror adjustment device; 104. Laser; 105. Laser detector; 201. Pulley assembly containing bearing; 202. Moving mirror steel wire rope; 203. Optical axis guide rail; 204. Power assembly. Detailed Implementation

[0029] Please see Figures 1-6 This invention provides a technical solution: a moving mirror scanning device for a high-resolution Fourier transform spectrometer, comprising: a moving mirror scanning device 100, which is provided with a moving mirror end corner reflector 1 for reflecting the measurement beam; a two-stage drive module, which includes a power component 204 for providing a first-stage stroke traction drive and a voice coil motor for providing a second-stage adjustment drive, the power component 204 being connected to the moving mirror scanning device 100 via a traction structure, and the voice coil motor mover 8 being fixedly connected to the moving mirror scanning device 100; and a position detection module, which includes a photoelectric switch for detecting... The moving mirror has a front position lever 2 and a rear position lever 9 for its travel limit positions, and a laser interference feedback module for generating interference signals in real time. The laser interference feedback module includes a laser 104, a beam splitter 101, a fixed-mirror end corner reflector 102, and a laser detector 105. The control module is electrically connected to the dual-stage drive module and the position detection module and is configured to: control the power component 204 to drive the moving mirror scanning device 100 to perform scanning motion; calculate the motion state deviation based on the interference signal fed back by the laser detector 105; and adjust the drive output of the voice coil motor according to the deviation closed loop.

[0030] The traction structure is a flexible rope transmission mechanism, and the control module is integrated on a circuit board, which is connected to the motor, photoelectric switch and detector through cables.

[0031] Specifically, the moving mirror scanning device 100 also includes an upper sliding bracket 6, a lower sliding bracket 14, and a moving mirror assembly base plate 16. The moving mirror end corner reflector 1 is installed on the front end of the upper sliding bracket 6 through the front assembly plate 3 of the sliding bracket. The voice coil motor mover 8 is installed on the rear end of the upper sliding bracket 6. The moving mirror assembly base plate 16 is fixedly connected to the lower sliding bracket 14. The voice coil motor stator 7 is positioned and fixed through the V-groove on the moving mirror assembly base plate 16.

[0032] The upper sliding bracket 6 and the lower sliding bracket 14 are connected to form a frame by four corner columns. The front assembly plate 3 of the sliding bracket is fixed to the front end of the upper sliding bracket 6 by screws. The voice coil motor mover 8 is fixed to the mounting surface at the rear end of the upper sliding bracket 6 by screws. A permanent magnet is embedded in the V-groove. After the corresponding edge of the voice coil motor stator 7 is embedded in the V-groove, it is magnetically attracted and fastened to the base plate 16 of the moving mirror assembly by screws. A rubber buffer pad 4 is installed at the rear end of the voice coil motor stator 7. A mounting plate 5 that can be matched with a grating ruler is fixedly installed on the side of the upper sliding bracket 6. A guide rod 17 is also included, one end of which is fixed to the front assembly plate 3 of the sliding bracket and the other end of which is fixed to the rear assembly plate 10 of the sliding bracket. The guide rod 17 passes through the gap between the voice coil motor stator 7 and the voice coil motor mover 8.

[0033] Spring steel spring pieces 12 are installed between the four corners of the upper sliding bracket 6 and the lower sliding bracket 14 to provide elastic support along the scanning axis.

[0034] Among them, the spring steel spring sheet 12 is rectangular, and its two ends are respectively inserted into the mounting grooves at the corresponding corners of the upper sliding bracket 6 and the lower sliding bracket 14. It is pressed and fixed from the upper and lower sides by the spring steel pressure block 11 and the spring sheet pressure block 13. The middle part of each spring sheet can be designed with a relief hole or a bending structure.

[0035] In this implementation scheme, the precise installation of the moving mirror end-angle reflector and voice coil motor, and their combination with the sliding bracket, provides precise scanning control and accurate positioning. Through the frame structure of the sliding bracket, the device remains stable during scanning, avoiding errors caused by vibration or instability. The design of the guide rod further improves the mechanical precision of the entire system, effectively preventing relative movement between the upper and lower sliding brackets and ensuring trajectory stability during the scanning process. The cooperation between the V-groove and the permanent magnet makes the stator and the base plate more firmly fixed, reducing unnecessary displacement and improving the driving force and efficiency of the motor. The application of spring steel spring sheets enhances the elastic support of the device, enabling it to adapt to different working conditions during scanning and avoiding excessive influence of external forces on the system.

[0036] Specifically, it also includes an optical axis guide rail 203 and multiple sliding bearings 15. The sliding bearings 15 are installed at the bottom of the moving mirror assembly base plate 16 and roll in cooperation with the optical axis guide rail 203 to form a rolling guide pair.

[0037] Among them, the sliding bearing 15 is a miniature linear ball bearing, which is installed in the bearing seat hole at the bottom of the moving mirror assembly base plate 16 by set screws. Four bearings are divided into two groups and symmetrically installed at the front and rear ends of one side of the base plate, with their axes forming a 30-degree angle with the vertical direction; another bearing is vertically installed in the middle of the other side of the base plate, and the optical axis guide rail 203 is fixed on the base by supports at both ends.

[0038] In this implementation scheme, the design of the optical axis guide rail and sliding bearing effectively improves the motion accuracy and stability of the moving mirror scanning device. The selection of miniature linear ball bearings ensures that the device has low friction during operation, thereby reducing motion resistance and making the entire system respond faster and run more smoothly. The symmetrically distributed bearing configuration ensures that the device can be evenly stressed during movement, effectively avoiding deformation or errors caused by uneven stress. The rolling fit between the bearings and the optical axis guide rail forms a highly efficient guide pair, enhancing the guidance during movement and ensuring the precise positioning of the moving mirror assembly. The support structure of the optical axis guide rail also enables the device to maintain stable operation for a longer period of time and reduces the impact of unstable motion trajectory.

[0039] Specifically, the traction structure includes a pulley assembly 201 containing bearings and a moving mirror steel wire rope 202. The power assembly 204 pulls the moving mirror scanning device 100 to move through the moving mirror steel wire rope 202 and the pulley assembly 201. The fixed mirror end angle reflector 102 is equipped with a fixed mirror adjustment device 103.

[0040] The pulley assembly 201 containing bearings includes a pulley, a pulley shaft, deep groove ball bearings and bearing seats installed at both ends of the shaft, and a moving mirror wire rope 202 is a coated wire rope. One end of the rope is fixed to the moving mirror scanning device 100 by a rope clamp. After passing through the pulley assembly 201 in sequence, the other end is connected to the drum of the power assembly 204. The fixed mirror adjustment device 103 is a multi-dimensional manual adjustment frame. It drives the flexible hinge through a micrometer head to adjust the pitch and yaw of the platform on which the fixed mirror end corner reflector 102 is installed.

[0041] In this implementation scheme, the motion accuracy and adjustability of the moving mirror scanning device are improved by designing a traction structure and a fixed mirror adjustment device. The cooperation between the pulley assembly and the internal bearing reduces friction and ensures smooth movement of the wire rope during traction, thereby improving the overall system's response speed and stability. The use of the moving mirror wire rope, combined with the power component, provides a stable driving force, enabling the moving mirror scanning device to complete the scanning task accurately and smoothly. The matching design of the fixed mirror end angle reflector and adjustment device realizes multi-dimensional adjustment functions, which can accurately adjust the pitch and yaw angles of the lens in actual operation, ensuring that the lens always maintains the optimal position during scanning. The overall design not only optimizes the traction force transmission of the device but also enhances the flexibility of lens adjustment, enabling the moving mirror scanning device to maintain high accuracy in different working environments.

[0042] Specifically, the control module executes the moving mirror scanning control process as follows:

[0043] The control power component 204 pulls the moving mirror scanning device 100 to move, causing the front position lever 2 to trigger the zero-position photoelectric switch at a pre-set position. This sets the interference signal count value output by the laser detector 105 to 0, completing the system zero-position calibration. Specifically:

[0044] The control module drives the stepper motor to slowly pull back the mirror scanning device 100. When the front position paddle 2 installed on the upper sliding bracket 6 first blocks the photoelectric switch beam, the output level of the photoelectric switch jumps from high to low, generating a falling edge trigger signal.

[0045] The control module then latches this moment as Simultaneously, the analog interference signal output by the laser detector 105 is captured, and its phase point is determined by the zero-crossing detection circuit or digital algorithm. Specifically, the zero-crossing point of the first interference signal sine wave immediately following the trigger signal, that is, the point where the signal voltage crosses from negative zero to positive, is taken as the reference point. The count value of the interference signal output by the laser detector 105 at that moment is set to 0, and the internal fringe counter N is reset to 0.

[0046] A smooth velocity planning trajectory is generated based on the target scanning speed and scanning length, specifically as follows:

[0047] Let the target be scanned at a constant speed. The total scan displacement is The displacements during both the acceleration and deceleration phases are acceleration is Then the speed planning trajectory for:

[0048] ;

[0049] in, To accelerate or decelerate time, For the acceleration segment displacement, the uniform velocity segment time This trajectory ensures a smooth start and stop for the scan, avoiding impact.

[0050] The control power component 204 drives the moving mirror scanning device 100 to begin scanning motion along the optical axis guide rail 203, so that its speed follows the speed-planned trajectory, specifically as follows:

[0051] The control module will generate speed commands The conversion relationship between the pulse frequency signal of the stepper motor and the actual pulse frequency signal is as follows: ,in The diameter of the pulley of the moving mirror steel wire rope 202 Stepper motor step angle (e.g., 1.8°) and differential numbers The transmission coefficient, which is jointly determined, is calculated using the following formula: ;

[0052] The stepper motor in the power assembly 204 is driven to rotate by the driver, and then the moving mirror scanning device 100 is pulled to move by the pulley assembly 201 and the moving mirror wire rope 202.

[0053] During the scanning motion, the interference signal output by the laser detector 105 is acquired and processed in real time to calculate the instantaneous actual speed of the moving mirror scanning device 100, which is as follows:

[0054] The analog signal output by laser detector 105 is ,in , This refers to the displacement of the moving mirror. For example, a laser wavelength of 632.8 nm. For amplitude, This is the initial phase;

[0055] After passing through an anti-aliasing filter, the signal is then processed by a high-speed analog-to-digital converter at a sampling frequency. (For example Sampling at 10MHz yields discrete sequences. ;

[0056] The phase change rate is demodulated in real time using digital signal processing algorithms. And then according to the formula Calculate the instantaneous actual velocity;

[0057] The deviation between the instantaneous actual velocity and the target velocity of the velocity-planned trajectory is calculated as follows:

[0058] In each control cycle (For example Within 100μs, calculate the velocity deviation. ;

[0059] Based on the deviation value and the feedforward compensation calculated from the difference between the target speed and the real-time speed, the drive current output to the voice coil motor mover 8 is adjusted in real time to complete the closed-loop regulation of the scanning speed. Specifically:

[0060] Total drive current ;

[0061] Feedback current Due to speed deviation The result is calculated by the digital PID controller:

[0062] ;

[0063] final The voice coil motor mover 8 is driven by a power amplifier.

[0064] In this implementation scheme, the motion control and speed regulation of the moving mirror scanning device are optimized through precise control processes and real-time adjustment mechanisms. Zero-position calibration of the system is achieved by triggering the photoelectric switch via the front position lever, providing a reliable reference point for subsequent scanning. Utilizing the interference signal from the laser detector and the zero-crossing detection circuit, the phase can be accurately calculated and the interference signal can be captured synchronously, ensuring high-precision positioning during the scanning process. Generating a smooth speed planning trajectory effectively avoids impacts during the scanning process, ensuring the stability of equipment operation. Dynamically adjusting the stepper motor pulse frequency and speed, combined with the real-time acquired interference signal, allows for precise calculation of the instantaneous actual speed and timely closed-loop adjustment, reducing deviations from the target speed and maintaining high-precision scanning speed. Combining feedforward compensation and PID control technology further improves the accuracy and stability of motion control, ensuring the precision of the scanning process.

[0065] Specifically, such as Figure 7 As shown, the specific steps for real-time acquisition and processing of the interference signal to calculate the instantaneous actual velocity are as follows:

[0066] The interference fringe signal output by laser detector 105 is subjected to analog-to-digital conversion and digital sampling, specifically as follows:

[0067] Interference signal After pre-amplification and anti-aliasing filtering, the signal is transmitted by a high-speed analog-to-digital converter at a fixed sampling frequency. Perform synchronous sampling to obtain discrete time series. ,in , The sampling period is The sample number is an integer.

[0068] The periodic zero-crossing points of the digital signal are identified, and stripe pulse counting is performed, specifically as follows:

[0069] For discrete sequences Zero-pass detection was performed when the conditions were met. and (Rising edge crosses zero) or and When the falling edge crosses zero, it is counted as a stripe pulse event, and the stripe counter N is incremented by 1;

[0070] Each complete stripe pulse corresponds to a change in the displacement of the moving mirror. ;

[0071] The signal waveform within the current fringe period is analyzed in real time to extract the real-time phase value within that period, specifically as follows:

[0072] Define a fringe period between two adjacent zero-crossing points, and take m sampling points within this period. The instantaneous phase is calculated using a digital quadrature demodulation algorithm;

[0073] First, the generation of the signal carrier frequency (about , (For coarse velocity estimation) Matched orthogonal reference signal and ,Will respectively with and Multiply and pass through a low-pass filter to obtain the in-phase component. and orthogonal components Then the real-time phase Continuous phase values ​​are obtained through phase unwinding. It varies from 0 to 2π within one stripe period;

[0074] Based on the stripe pulse count and the real-time phase value, the real-time displacement of the moving mirror scanning device 100 is calculated, specifically as follows:

[0075] Real-time displacement The integer stripe count N and the fractional phase The calculation formula is jointly determined as follows: ;

[0076] The instantaneous actual velocity of the moving mirror scanning device 100 is obtained by differentiating the real-time displacement, specifically as follows:

[0077] For displacement sequence For digital differentiation, the central difference method is used:

[0078] ;

[0079] To suppress differential noise, Perform low-pass digital filtering, for example, using a first-order infinite impulse response filter:

[0080] ;

[0081] in For filter coefficients 0 < <1.

[0082] In this implementation scheme, the interference signal is digitally sampled by a high-speed analog-to-digital converter, ensuring high-frequency capture and accurate sampling of the signal. Zero-crossing detection and fringe pulse counting accurately identify the periodic changes of the signal, obtaining real-time information on displacement changes. The phase value is analyzed by a digital quadrature demodulation algorithm, which can accurately calculate the instantaneous phase and deduce the real-time displacement based on it. Combining fringe pulse counting with the calculation of real-time phase value makes the measurement of displacement and velocity more accurate, avoiding the errors of traditional methods. To further improve accuracy, the real-time displacement is differentially calculated and low-pass filtered to effectively suppress differential noise, thereby obtaining high-precision instantaneous actual velocity.

[0083] Specifically, the calculation and generation of the feedforward compensation amount follow these steps:

[0084] Based on the motion characteristics of the moving mirror scanning device 100, a feedforward control model is established;

[0085] During the scanning process, the difference between the target velocity and the current velocity is calculated, specifically as follows:

[0086] In each control cycle Internally, calculate speed deviation The difference is used as the input to the feedforward control model.

[0087] The difference is input into the feedforward control model to calculate the theoretical compensation force, which is as follows:

[0088] Theoretical compensating force ,in This is the feedforward gain coefficient;

[0089] Based on the force constant of the voice coil motor, the theoretical compensation force is converted into the corresponding feedforward current compensation amount, specifically as follows:

[0090] Feedforward current compensation .

[0091] In this implementation scheme, a feedforward control model based on speed deviation is used to achieve rapid response and accurate compensation for the motion of the moving mirror scanning device. In each control cycle, the control module calculates the theoretical compensation force in real time based on the difference between the target speed and the real-time speed and converts it into feedforward current. After being superimposed with the feedback adjustment, it drives the voice coil motor, which effectively improves the dynamic response speed and tracking accuracy of the system and reduces speed fluctuations caused by mechanical inertia and external disturbances.

[0092] The specific steps for the control module to perform the scan endpoint safety control are as follows:

[0093] During the scanning process, the real-time position and velocity of the moving mirror scanning device 100 are continuously compared with the target velocity to calculate the velocity deviation value, which is as follows:

[0094] The control module in each fixed control cycle (For example Within 100 μs, the instantaneous actual velocity calculated from the laser interference signal. relative to target speed By comparison, the speed deviation is calculated. ;

[0095] This deviation value reflects the degree to which the actual motion of the moving mirror deviates from the ideal velocity. >0 indicates that the actual speed is relatively slow. <0 indicates that the actual speed is too fast;

[0096] Based on the deviation value, and combined with the feedforward compensation amount calculated based on the difference between the target speed and the real-time speed. Adjust the drive current output to the voice coil motor mover in real time;

[0097] Feedback adjustment amount Due to speed deviation Generated by a PID controller;

[0098] Final drive current The output is then amplified and sent to the voice coil motor mover 8 to achieve closed-loop fine-tuning of the moving mirror speed;

[0099] When the deviation value is positive, an acceleration command is sent to the power component 204, and at the same time, an active drive current in the same direction of motion is output to the voice coil motor mover 8. Specifically:

[0100] like >0 indicates that the actual speed is lower than the target speed and acceleration is required. At this time, a command to increase the pulse frequency is sent to the stepper motor driver of the power component 204 to increase the traction force of its stepper motor.

[0101] At the same time, according to the magnitude of the deviation, proportionally A positive drive current is generated and output to the voice coil motor mover 8, wherein... The proportionality coefficient enables the voice coil motor to generate thrust in the same direction, assisting the moving mirror in accelerating.

[0102] When the deviation value is negative, a deceleration command is sent to the power component 204, and at the same time, an active damping current opposite to the current direction of motion is output to the voice coil motor mover 8, specifically as follows:

[0103] like <0 indicates that the actual speed is higher than the target speed and deceleration is required. At this time, a command to reduce the pulse frequency is sent to the stepper motor driver of the power component 204 to reduce the traction force.

[0104] At the same time, proportionally based on the absolute value of the deviation Generates a reverse damping current, in which The damping coefficient is the force generated by the current, which is opposite to the direction of motion, producing a braking effect that slows down the moving mirror.

[0105] When the deviation is zero, the existing speed is maintained, specifically as follows:

[0106] like =0, meaning the actual speed is equal to the target speed, then the driving frequency of the current power component 204 and the driving current of the voice coil motor mover 8 remain unchanged, so that the moving mirror continues to move at a constant speed.

[0107] In this implementation scheme, the speed deviation is... Combined with feedforward compensation based on speed difference, real-time, dynamic, and high-precision closed-loop adjustment of the moving mirror scanning speed is achieved. When the speed deviates, the control module can quickly identify the direction and magnitude of the deviation, and simultaneously adjust the macroscopic traction force through the power component 204 and compensate for the microscopic force through the voice coil motor, forming a synergistic effect of coarse and fine adjustment. This dual-stage linkage mechanism not only ensures that the moving mirror strictly follows the preset speed trajectory throughout the entire scanning process, but also... This effectively suppresses speed fluctuations caused by factors such as mechanical friction, load changes, and external disturbances. Moreover, the rapid intervention of active damping current prevents speed overshoot and oscillation, significantly improving the stability and linearity of the scan. In addition, this control strategy also plays a role when approaching the end of the stroke, and can implement smooth deceleration in advance according to the speed deviation to avoid overshoot and impact, thereby protecting the mechanical structure of the device while ensuring high-resolution spectral measurement.

[0108] Specifically, the control module performs the following steps for online calibration of system parameters:

[0109] When the moving mirror scanning device 100 is in the stable and uniform scanning stage, a set of small sinusoidal test signals of a set frequency are superimposed on the driving current of the voice coil motor mover 8, specifically:

[0110] Let the current main drive current be Superimposed test signals ,in much smaller For example =0.01 , For the selected test frequency, such as 10Hz to 500Hz, the total current... ;

[0111] The interference signal output by the laser detector 105 is synchronously acquired, and the velocity modulation component caused by the test signal is extracted, specifically as follows:

[0112] Acquire interference signals and calculate instantaneous velocity ;

[0113] right Perform synchronous demodulation and then connect them to the appropriate frequency. and Multiply and then pass through a low-pass filter to obtain the frequency. In-phase response components at the location and orthogonal response components , forming a complex response vector ;

[0114] The amplitude ratio and velocity difference between the test signal and the system response signal are analyzed to identify and update the equivalent mass in the feedforward control model. Specifically:

[0115] The system at frequency Frequency response function amplitude at ;

[0116] In the low frequency band (Largely below the system's resonant frequency), the system's dynamics are mainly dominated by inertia, and its theoretical response amplitude is... ;

[0117] By comparing actual measurements The equivalent mass can be derived and updated by comparing it with the theoretical value. The estimated value:

[0118] ;

[0119] The amplitude ratio obtained from this This reflects the difference between the input test signal and the output speed response, i.e., the speed difference, and the updated... This will be used for the calculation of subsequent feedforward compensation.

[0120] In this implementation scheme, the control accuracy and system performance of the moving mirror scanning device are effectively improved through an online calibration mechanism. During the stable uniform scanning phase, by superimposing a small sinusoidal test signal of a set frequency, the system parameters can be calibrated in real time without affecting the normal operation of the system. By synchronously acquiring interference signals and demodulating them, the phase or velocity modulation components caused by the test signals can be accurately extracted, thereby evaluating the dynamic response of the system in real time. By analyzing the amplitude ratio and velocity difference between the test signal and the system response signal, the equivalent quality of the system can be accurately identified. By comparing with the theoretical values, the parameters in the feedforward control model are dynamically updated, and the updated equivalent quality can be used in subsequent feedforward compensation calculations.

[0121] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0122] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A moving mirror scanning device for a high-resolution Fourier transform spectrometer, characterized in that, include: The moving mirror scanning device (100) is equipped with a moving mirror end corner reflector (1) for reflecting the measurement beam. The dual-stage drive module includes a power assembly (204) for providing primary stroke traction drive and a voice coil motor for providing secondary adjustment drive. The power assembly (204) is connected to the moving mirror scanning device (100) via a traction structure, and the voice coil motor mover (8) is fixedly connected to the moving mirror scanning device (100). The position detection module includes a front position lever (2) and a rear position lever (9) equipped with photoelectric switches for detecting the travel limit position of the moving mirror, and a laser interference feedback module for generating interference signals in real time. The laser interference feedback module includes a laser (104), a beam splitter (101), a fixed mirror end corner reflector (102), and a laser detector (105). The control module, electrically connected to the dual-stage drive module and the position detection module, is configured as follows: The control power unit (204) drives the moving mirror scanning device (100) to perform scanning motion; Motion state deviation is calculated based on the interference signal fed back by the laser detector (105); The drive output of the voice coil motor is adjusted according to the deviation closed loop.

2. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 1, characterized in that, The moving mirror scanning device (100) also includes an upper sliding bracket (6), a lower sliding bracket (14) and a moving mirror assembly base plate (16). The moving mirror end corner reflector (1) is installed on the front end of the upper sliding bracket (6) through the front assembly plate (3) of the sliding bracket. The voice coil motor mover (8) is installed on the rear end of the upper sliding bracket (6). The moving mirror assembly base plate (16) is fixedly connected to the lower sliding bracket (14). The voice coil motor stator (7) is positioned and fixed through the V-groove on the moving mirror assembly base plate (16).

3. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 2, characterized in that, Spring steel spring sheets (12) are installed between the four corners of the upper sliding bracket (6) and the lower sliding bracket (14) to provide elastic support along the scanning axis.

4. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 1, characterized in that, It also includes an optical axis guide rail (203) and multiple sliding bearings (15). The sliding bearings (15) are installed at the bottom of the moving mirror assembly base plate (16) and roll in cooperation with the optical axis guide rail (203) to form a rolling guide pair.

5. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 1, characterized in that, The traction structure includes a pulley assembly (201) containing bearings and a moving mirror wire rope (202). The power assembly (204) pulls the moving mirror scanning device (100) through the moving mirror wire rope (202) and the pulley assembly (201). The fixed mirror end angle reflector (102) is equipped with a fixed mirror adjustment device (103).

6. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 1, characterized in that, The control module executes the moving mirror scanning control process as follows: The control power component (204) pulls the moving mirror scanning device (100) to move, so that the front position lever (2) triggers the zero position photoelectric switch of the pre-set position, and sets the interference signal count value output by the laser detector at this time to 0, thus completing the system zero position calibration; Generate a smooth velocity planning trajectory based on the target scanning speed and scanning length; The control power component (204) drives the moving mirror scanning device (100) to start scanning motion along the optical axis guide rail (203), so that its speed follows the speed planning trajectory; During the scanning motion, the interference signal output by the laser detector (105) is collected and processed in real time to calculate the instantaneous actual speed of the moving mirror scanning device (100). Calculate the deviation between the instantaneous actual velocity and the target velocity of the velocity planning trajectory; Based on the deviation value and the feedforward compensation amount calculated based on the difference between the target speed and the real-time speed, the drive current output to the voice coil motor mover (8) is adjusted in real time to complete the closed-loop regulation of the scanning speed.

7. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 6, characterized in that, The specific steps for real-time acquisition and processing of interference signals to calculate the instantaneous actual velocity are as follows: The interference fringe signal output by the laser detector (105) is subjected to analog-to-digital conversion and digital sampling; Identify the periodic zero-crossing points of the digital signal and count the stripe pulses; The signal waveform within the current stripe period is analyzed in real time, and the real-time phase value within that period is determined. The real-time displacement of the moving mirror scanning device (100) is calculated based on the stripe pulse count and the real-time phase value. The instantaneous actual velocity of the moving mirror scanning device (100) is obtained by performing differential calculation on the real-time displacement.

8. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 6, characterized in that, The specific steps for calculating and generating the feedforward compensation amount are as follows: Based on the motion characteristics of the moving mirror scanning device (100), a feedforward control model is established; During the scanning process, the difference between the target velocity and the current velocity is calculated; The difference is input into the feedforward control model to calculate the theoretical compensation force. Based on the force constant of the voice coil motor, the theoretical compensation force is converted into the corresponding feedforward current compensation amount.

9. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 6, characterized in that, The specific steps for the control module to perform the scan endpoint safety control are as follows: During the scanning process, the real-time position and speed of the moving mirror scanning device (100) are continuously compared with the target speed to calculate the speed deviation value; based on the deviation value and combined with the feedforward compensation amount calculated based on the difference between the target speed and the real-time speed, the drive current output to the voice coil motor mover is adjusted in real time. When the deviation value is positive, an acceleration command is sent to the power component (204), and at the same time, an active drive current with the same direction of motion is output to the voice coil motor mover (8); When the deviation value is negative, a deceleration command is sent to the power component (204), and at the same time, an active damping current opposite to the current motion direction is output to the voice coil motor mover (8); When the deviation is zero, the current speed remains unchanged.

10. The moving mirror scanning device for a high-resolution Fourier transform spectrometer according to claim 6, characterized in that, The specific steps for the control module to perform online calibration of system parameters are as follows: When the moving mirror scanning device (100) is in the stable and uniform scanning stage, a set of small sinusoidal test signals of a set frequency are superimposed on the driving current of the voice coil motor mover (8); The interference signal output by the laser detector (105) is acquired synchronously, and the phase or velocity modulation component caused by the test signal is extracted. Analyze the amplitude ratio and velocity difference between the test signal and the system response signal to identify and update the equivalent mass in the feedforward control model.

Images