Hyperspectral imaging device and fabry-perot resonator, control method

Abstract

The application discloses a hyperspectral imaging device and a Fabry-Perot resonant cavity, and a control method, the resonant cavity comprising a substrate and a substrate, a piezoelectric ceramic, a voltage driving circuit, a control module, a to-be-measured capacitor, and a capacitor detection module; the number of the to-be-measured capacitors is the same as that of the piezoelectric ceramic and one-to-one correspondence; the capacitor detection module comprises an excitation signal generation module, a signal receiving module and a Fourier transform module; the excitation signal generation module is connected with the control module and the to-be-measured capacitor, the signal receiving module is connected with the to-be-measured capacitor, and the output end of the signal receiving module is connected with the control module through the Fourier transform module; the control module calculates the capacitance value of the to-be-measured capacitor according to the frequency domain signal output by the Fourier transform module, calculates the gap between the substrate and the substrate according to the capacitance value, and controls the driving voltage output by the voltage driving circuit according to the gap. The application can compensate for the hysteresis effect and improve the resonant frequency accuracy of the resonant cavity.

Description

Technical Field

[0001] This invention belongs to the field of circuit design technology, and particularly relates to a hyperspectral imaging device, a Fabry-Perot resonator, and a control method. Background Technology

[0002] In imaging spectrometers, the main function of the spectrometer is to segment the spectral bands, allowing for separate imaging of each segmented band on different detectors. Prisms and gratings are traditional dispersive elements in imaging spectrometers; however, such spectrometers are not only structurally complex but also large in size and weight. With the advancement of detector scanning performance to focal plane array scanning, hyperspectral imaging has become the mainstream imaging system, requiring higher spectral resolution and necessitating the selection of new spectrometers.

[0003] To meet the requirements of higher spectral resolution, tunable filters have emerged. With the rapid development of FP (Fabry-Perot) tunable filter design and fabrication technology, their application in infrared spectrometers and infrared hyperspectral imaging has received increasing attention. Currently, FP tunable filters are a typical application technology of electro-optic tunable filters, used to solve the problem of higher spectral resolution.

[0004] Existing FP tunable filters typically incorporate piezoelectric ceramics in their resonant cavities. The tuning frequency of the Fabry-Perot resonator is adjusted by changing the deformation of the piezoelectric ceramic through a voltage-driven circuit, thereby regulating the gap between the resonator substrate and the Fabry-Perot resonator. However, due to the nonlinearity and hysteresis of the piezoelectric ceramic, the deformation varies under the same driving voltage. Consequently, gap errors in the resonator result in lower tuning frequency accuracy for the Fabry-Perot resonator.

[0005] Depend on Figure 1 The hysteresis curves shown indicate that: 1. The displacement curve exhibits nonlinearity as the driving voltage increases or decreases linearly; 2. The displacement curves do not coincide when the driving voltage increases or decreases linearly, meaning that the deformation of the piezoelectric ceramic (or the gap of the resonant cavity) is different under the same driving voltage, resulting in positioning errors. Summary of the Invention

[0006] The purpose of this invention is to provide a hyperspectral imaging device, a Fabry-Perot resonator, and a control method to solve the problem of low accuracy of the tuning frequency of the Fabry-Perot resonator due to the positioning error of the resonator gap under the same driving voltage caused by the nonlinearity and hysteresis effect of piezoelectric ceramics.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: a Fabry-Perot resonant cavity, comprising a substrate and a plate disposed opposite to each other, a piezoelectric ceramic disposed on the substrate and / or plate, a voltage driving circuit connected to the piezoelectric ceramic, and a control module connected to the voltage driving circuit; the Fabry-Perot resonant cavity further comprises: a capacitor under test and a capacitance detection module; the electrodes of the capacitor under test are disposed on the substrate and / or plate, and the number of capacitors under test is the same as the number of piezoelectric ceramics and corresponds one-to-one;

[0008] The capacitance detection module includes an excitation signal generation module, a signal receiving module, and a Fourier transform module; the input terminal of the excitation signal generation module is connected to the control module, and the output terminal of the excitation signal generation module is connected to the first electrode of the capacitor under test; the input terminal of the signal receiving module is connected to the second electrode of the capacitor under test, and the output terminal of the signal receiving module is connected to the control module through the Fourier transform module.

[0009] The excitation signal generation module is used to generate an excitation signal; the signal receiving module is used to process the received signal; the Fourier transform module is used to convert the signal processed by the signal receiving module into a frequency domain signal; the control module is used to calculate the capacitance value of the capacitor under test based on the frequency domain signal, calculate the gap between the substrate and the substrate based on the capacitance value, and control the driving voltage output by the voltage driving circuit based on the gap to achieve gap error compensation.

[0010] Furthermore, the excitation signal generation module includes a DDS control unit, a first D / A conversion unit, and an impedance matching unit connected in sequence; the DDS control unit is used to generate a phase table of a sinusoidal signal under the control of the control module; the first D / A conversion unit is used to generate a sinusoidal signal according to the phase table; the impedance matching unit is used to perform impedance matching on the sinusoidal signal and input the impedance-matched sinusoidal signal to the capacitor under test.

[0011] The signal receiving module includes a transconductance amplification unit, a filtering unit, and a first A / D conversion unit connected in sequence.

[0012] Furthermore, the transconductance amplification unit is based on a dual-channel voltage feedback operational amplifier of model OPA2810.

[0013] Furthermore, the specific formula for calculating the capacitance value of the capacitor under test is as follows:

[0014]

[0015] Among them, C x C represents the capacitance value of the capacitor under test. FThis is the capacitance value of the feedback capacitor in the transconductance amplifier unit; I is the real part of the frequency domain signal, and Q is the imaginary part of the frequency domain signal.

[0016] Furthermore, the voltage driving circuit includes a DAC compensation unit, and a second D / A conversion unit, a linear amplification unit, and a high-voltage driving unit connected in sequence; the input terminal of the DAC compensation unit is connected to the control module, and the output terminal of the DAC compensation unit is connected to the linear amplification unit.

[0017] Furthermore, the high-voltage drive unit includes a high-voltage amplification unit and a high-voltage power supply; the output terminal of the high-voltage power supply is connected to the power supply terminal of the high-voltage amplification unit; the high-voltage amplification unit is based on a high-voltage high-speed power operational amplifier of model PA78.

[0018] Furthermore, the frequency of the excitation signal is 30K to 100K.

[0019] Based on the same concept, the present invention also provides a control method for the Fabry-Perot resonator as described above, comprising the following steps:

[0020] An excitation signal is generated and input to the capacitor under test;

[0021] The signal is obtained from the capacitor under test, and the obtained signal is amplified, filtered and converted by an analog-to-digital converter.

[0022] The processed signal is converted into a frequency domain signal;

[0023] The capacitance value of the capacitor under test is calculated based on the frequency domain signal, the gap between the substrate and the substrate is calculated based on the capacitance value, and the driving voltage output by the control voltage driving circuit is controlled based on the gap to achieve compensation for the gap error.

[0024] Based on the same concept, the present invention also provides a hyperspectral imaging device, including the Fabry-Perot resonator as described above.

[0025] Beneficial effects

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] This invention first detects the capacitance value of the capacitor under test, then calculates the gap of the resonant cavity based on the capacitance value, and finally adjusts the driving voltage of the piezoelectric ceramic according to the gap to make the gap of the resonant cavity reach the target gap. This realizes the compensation of the resonant cavity gap positioning error (i.e., compensation of the hysteresis effect of the piezoelectric ceramic), enables the piezoelectric ceramic to work linearly, and improves the accuracy of the tuning frequency of the Fabry-Perot resonant cavity. Attached Figure Description

[0028] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a curve of the hysteresis effect of piezoelectric ceramics in the background technology of this invention;

[0030] Figure 2 This is a schematic diagram of the Fabry-Perot resonator structure in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the arrangement of three piezoelectric ceramics in an embodiment of the present invention;

[0032] Figure 4 This is an electrode arrangement diagram on the substrate in an embodiment of the present invention;

[0033] Figure 5 This is an electrode arrangement diagram on the substrate in an embodiment of the present invention;

[0034] Figure 6 This is a structural block diagram of the capacitance detection module in an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the anti-aliasing filter in an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the transconductance amplification unit in an embodiment of the present invention;

[0037] Figure 9 This is a block diagram of the voltage driving circuit in an embodiment of the present invention.

[0038] Wherein, 1-substrate, 11-first piezoelectric ceramic, 12-second piezoelectric ceramic, 13-third piezoelectric ceramic, 2-substrate. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0041] like Figure 2 As shown, the Fabry-Perot resonant cavity provided in this embodiment of the invention includes a substrate 1 and a substrate 2 disposed opposite to each other, a piezoelectric ceramic disposed on the substrate 1, a voltage driving circuit connected to the piezoelectric ceramic, a control module connected to the voltage driving circuit, a capacitor under test, and a capacitance detection module. The electrodes of the capacitor under test are disposed on the substrate 1 and / or the substrate 2 and connected to the capacitance detection module. The capacitance detection module is connected to the control module.

[0042] like Figure 3 As shown, in this embodiment, the piezoelectric ceramics include three types: a first piezoelectric ceramic 11, a second piezoelectric ceramic 12, and a third piezoelectric ceramic 13. All three piezoelectric ceramics are disposed on the substrate 1. Each piezoelectric ceramic operates under the driving voltage of the voltage driving circuit, thereby adjusting the gap between the substrate 1 and the substrate 2.

[0043] The number of capacitors to be tested corresponds one-to-one with the number of piezoelectric ceramics, so that the driving voltage of the corresponding piezoelectric ceramic can be adjusted according to the capacitance value of a particular capacitor to be tested, thereby achieving gap adjustment. In this embodiment, there are 3 piezoelectric ceramics, resulting in 3 capacitors to be tested. Each capacitor to be tested includes a first electrode and a second electrode. The first electrode and the second electrode can both be disposed on substrate 1, both on substrate 2, or both on substrate 1 and substrate 2 respectively. Figure 4 and 5 As shown, electrodes D31 to D36 are provided on substrate 1, distributed around the pixel area, and electrodes D41 to D43 are provided on substrate 2. In a first embodiment, electrodes D31 and D32 can form a capacitor under test, electrodes D35 and D36 can form a capacitor under test, and electrodes D33 and D34 can form a capacitor under test. In a second embodiment, electrodes D41 (second electrode) and D31 and D32 (first electrodes) can form a capacitor under test, electrodes D42 (second electrode) and D33 and D34 (first electrodes) can form a capacitor under test, and electrodes D43 (second electrode) and D35 and D36 (first electrodes) can form a capacitor under test. In a third embodiment, electrodes D31 and D33 can form a capacitor under test, electrodes D32 and D34 can form a capacitor under test, and electrodes D35 and D36 can form a capacitor under test. There is no strict correspondence between the capacitor under test and the piezoelectric ceramic; one capacitor under test corresponds to one piezoelectric ceramic. For example, the capacitor under test formed by electrodes D31 and D32 corresponds to the second piezoelectric ceramic 12, the capacitor under test formed by electrodes D33 and D34 corresponds to the third piezoelectric ceramic 13, and the capacitor under test formed by electrodes D35 and D36 corresponds to the first piezoelectric ceramic 11. The specific design parameters of each electrode are shown in Table 1. The electrode area and capacitance value can be designed and adjusted according to actual needs.

[0044] Table 1 Design parameters for each electrode

[0045]

[0046] like Figure 6 As shown, the capacitance detection module includes an excitation signal generation module, a signal receiving module, and a Fourier transform module. The input terminal of the excitation signal generation module is connected to the control module, and the output terminal of the excitation signal generation module is connected to the first electrode of each capacitor under test. The input terminal of the signal receiving module is connected to the second electrode of each capacitor under test, and the output terminal of the signal receiving module is connected to the control module through the Fourier transform module. The excitation signal generation module generates an excitation signal and inputs it to each capacitor under test. The signal receiving module receives signals from each capacitor under test and processes the received signals. The Fourier transform module converts the processed signals from the signal receiving module into frequency domain signals. The control module calculates the capacitance value of the capacitor under test based on the frequency domain signal, calculates the gap between the substrate and the substrate based on the capacitance value, and controls the driving voltage output by the voltage driving circuit based on the gap to compensate for the gap error.

[0047] In one specific embodiment of the present invention, such as Figure 6 As shown, the excitation signal generation module includes a DDS control unit, a first D / A conversion unit, and an impedance matching unit connected in sequence; the signal receiving module includes a transconductance amplification unit, a filtering unit, and a first A / D conversion unit connected in sequence. The DDS control unit generates a phase table for the sinusoidal signal under the control of the control module; the first D / A conversion unit generates the sinusoidal signal according to the phase table; and the impedance matching unit performs impedance matching on the sinusoidal signal and inputs the impedance-matched sinusoidal signal to each capacitor under test.

[0048] In this embodiment, the excitation signal is a sinusoidal signal. The first D / A conversion unit can directly generate the required sinusoidal signal using the DAC of the STM32F407 ARM chip, and the frequency and amplitude of the sinusoidal signal are controllable. The designed excitation signal frequency is 30K to 100K. The first D / A conversion unit (12-bit) is combined with DMA, buffered in ROM, and then the data is updated by DMA using an interrupt signal generated by a timer. The interrupt frequency of the timer is the sampling rate of the DAC refresh. The maximum clock of the STM32F407 is 168MHz. After passing through the clock tree, the refresh frequency given to the timer can reach 4MHz, which is sufficient for a sinusoidal signal of 30K to 100K. To ensure amplitude stability, the DAC reference VREF+ needs to be a high-precision, low-noise reference source.

[0049] The capacitance value of the capacitor under test is between 200pF and 820pF. The output impedance is related to the frequency of the excitation signal; the higher the frequency, the lower the output impedance. In the circuit design, an excitation signal of 30K to 100K is selected to ensure the capacitance reactance of the capacitor under test and the feedback resistance R of the transconductance amplifier unit. F It can match well and ensure V OUT The output signal range is [0.411V, 2.409V], which allows for full utilization of the ADC's effective range.

[0050] In one specific embodiment of the present invention, the transconductance amplification unit is based on a dual-channel voltage feedback operational amplifier, model OPA2810. The OPA2810 has an input bias current of 2pA, unity-gain stability, a signal bandwidth of 105MHz, an open-loop gain of 120dB, and a gain-bandwidth stage of 70dB. When the signal frequency is <100kHz, its open-loop gain can be maintained above 60dB, which significantly reduces the measurement error introduced by the op-amp's "virtual open circuit," and the voltage noise is...

[0051] The filtering unit in the signal receiving module is an anti-aliasing filter. Let the frequency of the excitation signal be f. According to the Nyquist sampling theorem, in order to distinguish the effective signal without distortion, the signal sampling rate must at least satisfy f. s If the frequency of the excitation signal is at most 100kHz (≥2*f), then the sampling rate of the ADC must be at least 200kHz. In practical engineering, it is generally taken as 5 to 10 times, that is, the sampling rate of the ADC is 500kHz to 1MHz. Assuming the sampling rate of the ADC is 1MHz, then the 3dB cutoff point of the anti-aliasing filter is 500kHz. The design of the anti-aliasing filter is as follows: Figure 7 As shown, the 3dB cutoff frequency of the circuit is 511K.

[0052] The STM32F407 comes with three 12-bit successive approximation ADC chips, each with 16 channels and a maximum sampling rate of 2.4MHz. Based on the above analysis, its bit depth and sampling rate meet the circuit design requirements. In addition, the three ADCs can support parallel measurement of three capacitors under test.

[0053] like Figure 8 The circuit diagram of the transconductance amplifier unit shown is C. x R represents the capacitor under test. F C represents the feedback resistor. F This represents the feedback capacitor, assuming a sinusoidal signal V is applied to the first electrode of the capacitor under test. TX =sin(2πft), the amplitude of the sinusoidal signal is 1V, and f is the frequency of the sinusoidal signal. Then, from the capacitance C under test... x The signal received by the second electrode, after being amplified by the transconductance amplifier unit, is:

[0054]

[0055] when Then, equation (1) can be simplified to:

[0056]

[0057] The capacitance C of the capacitor under test x The measurement is converted into a signal V RX The amplitude and phase of the signal are measured. In this embodiment, a Fourier transform module is used to measure the amplitude and phase of the signal V. RX The signal V is processed to calculate its amplitude and phase. RX After processing by the filtering unit and the first A / D conversion unit, it becomes:

[0058]

[0059] Among them, A and These represent the amplification factor and phase shift introduced during processing by the transconductance amplification unit and the filtering unit, respectively.

[0060] For signal V RX By using a multiplier to simultaneously multiply SIN and COS, and then passing the signal through a filter, the real part I and the imaginary part Q of the frequency domain signal can be obtained. Finally, C can be calculated using the resulting I / Q signal. x .

[0061] For Part I Using the product-to-sum formula for trigonometric functions, we can obtain:

[0062]

[0063] After filtering

[0064] Similarly, we can obtain

[0065] Using cosx 2 +sinx 2 =1, final C x Solving for the given information yields:

[0066]

[0067] Among them, C x C represents the capacitance value of the capacitor under test. F This is the capacitance value of the feedback capacitor in the transconductance amplifier unit; I is the real part of the frequency domain signal, and Q is the imaginary part of the frequency domain signal.

[0068] In one specific embodiment of the present invention, such as Figure 9 As shown, the voltage drive circuit includes a DAC compensation unit, and a second D / A conversion unit, a linear amplifier unit, and a high-voltage drive unit connected in sequence. The input terminal of the DAC compensation unit is connected to the control module, and the output terminal of the DAC compensation unit is connected to the linear amplifier unit. Considering that the drive voltage frequency is ≥100Hz, its design principle is consistent with the excitation signal design principle. The second D / A conversion unit uses TI's DAC121S101 12-bit DAC. Considering the stability of the output amplitude, its reference power supply needs to be selected as a low-noise, high-precision reference source.

[0069] The high-voltage drive unit includes a high-voltage amplifier unit and a high-voltage power supply. The output terminal of the high-voltage power supply is connected to the power supply terminal of the high-voltage amplifier unit. The high-voltage amplifier unit is based on a PA78 high-voltage high-speed power operational amplifier. The PA78 has a high power supply rejection ratio, which can reduce the requirements for the voltage regulation circuit. The high-voltage power supply is selected from the GSA12100HS-8 module power supply, which can simplify the power supply circuit design.

[0070] Under the control of the control module, the second D / A conversion unit (12-bit) generates the required voltage waveform. This waveform is then amplified by a linear amplifier and a high-voltage amplifier before being applied to the piezoelectric ceramic to adjust its micro-displacement. Since the linear amplifier circuit and the high-voltage drive unit introduce system errors, a DAC compensation unit is added to the actual circuit. This unit is calibrated to compensate for the circuit's fixed errors, ensuring that the voltage applied to the piezoelectric ceramic is consistent with the designed drive voltage.

[0071] In this embodiment, the piezoelectric ceramic is model PA3JEW. Based on the inherent characteristics of the piezoelectric ceramic and the design requirements, the voltage drive circuit for the piezoelectric ceramic requires the following: continuously adjustable output voltage from 0 to 100V; a drive load capacitor of 95nF; a tuning frequency ≥100Hz; a tuning rate ≥100µs; and drive waveforms of DC, sine wave, and square wave.

[0072] The control module calculates the gap between the substrate and the platen based on the capacitance value of the capacitor under test, and controls the driving voltage output by the voltage driving circuit according to this gap to compensate for the gap error. For three-channel piezoelectric ceramics, the relationship between the driving voltage of each piezoelectric ceramic and the capacitance value of the corresponding capacitor under test needs to be fitted so that the driving voltage can be adjusted according to the capacitance value of the capacitor under test.

[0073] The fitted sample data consists of the capacitance value and corresponding voltage value of the capacitor under test recorded during capacitance measurement for each piezoelectric ceramic. The form of the fitting function is determined by the recorded actual sample data. The linear / nonlinear relationship is evaluated by plotting pairs of sample data points. If the capacitance-voltage relationship in the sample data is linear, a monomial fitting function is used, i.e., V = aC + b (where V is the driving voltage, C is the capacitance value of the capacitor under test, and a and b are the parameters to be solved). If the capacitance-voltage relationship is nonlinear, a polynomial fitting function is used, such as a quadratic polynomial, i.e., V = aC 2 +bC+c. The parameters of the fitting function will be solved using the least squares method, minimizing the sum of the squares of the differences between the actual voltage values ​​of all sample data and the V calculated by the fitting function based on the actual capacitance value C. The function parameters are obtained by ensuring that the partial derivatives of the fitting function with respect to each parameter are zero. After obtaining the capacitance values ​​of the three capacitors to be measured and the fitting functions of the driving voltage, each piezoelectric ceramic can adjust its voltage value according to its respective fitting function to obtain the target capacitance value, thus obtaining the target gap.

[0074] The fit function can be evaluated using the coefficient of determination (R-squared), which ranges from 0 to 1. The closer the value is to 1, the better the fit.

[0075] In the Fabry-Perot resonant cavity described in this invention, the excitation signal of the capacitor under test and the driving voltage of the piezoelectric ceramic are separate and independent, avoiding the influence of the 100V high-voltage driving of the piezoelectric ceramic on the capacitor detection module (a shield can also be set outside the capacitor detection module). This invention first detects the capacitance value of the capacitor under test, then calculates the gap of the resonant cavity based on the capacitance value, and finally adjusts the driving voltage of the piezoelectric ceramic according to the gap to make the gap of the resonant cavity reach the target gap. This achieves compensation for the positioning error of the resonant cavity gap (i.e., compensation for the hysteresis effect of the piezoelectric ceramic), enabling the piezoelectric ceramic to work linearly and improving the tuning frequency accuracy of the Fabry-Perot resonant cavity. By adjusting the gap between the substrate and the platen using three or more piezoelectric ceramics and the capacitor under test, the parallelism between the substrate and the platen can be ensured, that is, the parallelism of the resonant cavity can be ensured, thereby ensuring the uniformity of the transmission characteristics of the light-transmitting aperture of the resonant cavity.

[0076] Based on the same concept, embodiments of the present invention also provide a control method for the Fabry-Perot resonator as described above, comprising the following steps:

[0077] Step 1: Under the control of the control module, the excitation signal generation module generates an excitation signal and inputs the excitation signal to each capacitor under test;

[0078] Step 2: Obtain a signal from each of the capacitors under test, and amplify, filter, and perform AD conversion on the obtained signals;

[0079] Step 3: Convert the processed signal into a frequency domain signal;

[0080] Step 4: Calculate the capacitance value of the capacitor under test based on the frequency domain signal, calculate the gap between the substrate and the substrate based on the capacitance value, and control the driving voltage output by the voltage driving circuit based on the gap to achieve gap error compensation.

[0081] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A Fabry-Perot resonant cavity, comprising a substrate and a plate disposed opposite to each other, a piezoelectric ceramic disposed on the substrate and / or plate, a voltage driving circuit connected to the piezoelectric ceramic, and a control module connected to the voltage driving circuit; characterized in that, The resonant cavity further includes: a capacitor under test and a capacitance detection module; the electrodes of the capacitor under test are disposed on the substrate and / or the substrate, and the number of capacitors under test is the same as the number of piezoelectric ceramics and corresponds one-to-one; The capacitance detection module includes an excitation signal generation module, a signal receiving module, and a Fourier transform module; the input terminal of the excitation signal generation module is connected to the control module, and the output terminal of the excitation signal generation module is connected to the first electrode of the capacitor under test; the input terminal of the signal receiving module is connected to the second electrode of the capacitor under test, and the output terminal of the signal receiving module is connected to the control module through the Fourier transform module. The excitation signal generation module includes a DDS control unit, a first D / A conversion unit, and an impedance matching unit connected in sequence, used to generate a sinusoidal excitation signal with a frequency of 30kHz~100kHz under the control of the control module; the signal receiving module includes a transconductance amplification unit, a filtering unit, and a first A / D conversion unit connected in sequence, used to amplify, filter, and perform analog-to-digital conversion on the received signal; the Fourier transform module is used to convert the signal processed by the signal receiving module into a frequency domain signal; the control module is used to calculate the capacitance value of the capacitor under test based on the real and imaginary parts of the frequency domain signal, calculate the gap between the substrate and the substrate based on the capacitance value, and control the driving voltage output by the voltage driving circuit based on the gap to achieve gap error compensation.

2. The Fabry-Perot resonator according to claim 1, characterized in that: The DDS control unit is used to generate a phase table of sinusoidal signals under the control of the control module; the first D / A conversion unit is used to generate a sinusoidal signal according to the phase table; the impedance matching unit is used to perform impedance matching on the sinusoidal signal and input the impedance-matched sinusoidal signal to the capacitor under test.

3. The Fabry-Perot resonator according to claim 1, characterized in that: The transconductance amplification unit is based on a dual-channel voltage feedback operational amplifier, model OPA2810.

4. The Fabry-Perot resonator according to claim 1, characterized in that: The specific formula for calculating the capacitance value of the capacitor under test is as follows: in, The capacitance value is the value of the capacitor to be tested. This is the capacitance value of the feedback capacitor in the transconductance amplifier unit; I is the real part of the frequency domain signal, and Q is the imaginary part of the frequency domain signal.

5. The Fabry-Perot resonator according to any one of claims 1 to 4, characterized in that: The voltage driving circuit includes a DAC compensation unit, and a second D / A conversion unit, a linear amplification unit, and a high-voltage driving unit connected in sequence; the input terminal of the DAC compensation unit is connected to the control module, and the output terminal of the DAC compensation unit is connected to the linear amplification unit.

6. The Fabry-Perot resonator according to claim 5, characterized in that: The high-voltage drive unit includes a high-voltage amplification unit and a high-voltage power supply; the output terminal of the high-voltage power supply is connected to the power supply terminal of the high-voltage amplification unit; the high-voltage amplification unit is based on a high-voltage high-speed power operational amplifier of model PA78.

7. The Fabry-Perot resonator according to claim 1, characterized in that: The data for both the piezoelectric ceramic and the capacitor under test are three or more.

8. A method for controlling a Fabry-Perot resonator as described in any one of claims 1 to 7, characterized in that, The method includes the following steps: An excitation signal is generated and input to the capacitor under test; The signal is obtained from the capacitor under test, and the obtained signal is amplified, filtered and converted by an analog-to-digital converter. The processed signal is converted into a frequency domain signal; The capacitance value of the capacitor under test is calculated based on the frequency domain signal, the gap between the substrate and the substrate is calculated based on the capacitance value, and the driving voltage output by the control voltage driving circuit is controlled based on the gap to achieve compensation for the gap error.

9. A hyperspectral imaging device, characterized in that, The device includes the Fabry-Perot resonator as described in any one of claims 1 to 7.

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