Measurement method, system and device based on mixed frequency modulation, computer equipment and readable storage medium

Abstract

The invention relates to a measurement method, system and device based on hybrid frequency modulation, computer equipment and a readable storage medium. The method comprises the following steps: carrying out interference on positive and negative frequency sweeping sideband components of a first modulation signal and a reflection signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulation signal is obtained by performing frequency sweeping sideband modulation on output light of a light source by a first modulator, and the reflection signal is obtained by reflecting the received first modulation signal by a target object; performing interference on the second modulation signal and the zero-frequency component of the reflection signal to obtain a second interference signal; determining vibration information of the target object based on the second interference signal; and the second modulation signal is obtained by performing fixed-frequency and frequency-shift modulation on the output light through a second modulator. By adopting the method, multi-dimensional measurement of the to-be-measured object can be realized.

Description

Technical Field

[0001] The present application relates to the field of laser measurement technology, and in particular to a measurement method, system, device, computer equipment and readable storage medium based on hybrid frequency modulation. Background Art

[0002] Optical frequency sweep coherent ranging systems are widely used in many fields such as autonomous driving, remote sensing and aerospace due to their non-contact measurement, anti-electromagnetic interference, and synchronous demodulation of distance and speed. The frequency sweep coherent ranging system in related technologies only has the ability to measure distance and speed. Due to the limitation of the frequency sweep bandwidth, its ranging resolution is generally at the millimeter level, making it difficult to capture tiny vibration information. Therefore, when using the traditional frequency sweep coherent ranging system to measure the object to be measured, the measurement index is single and the measurement efficiency is low. Summary of the invention

[0003] Based on this, it is necessary to provide a measurement method, system, device, computer equipment and readable storage medium based on mixed frequency modulation to address the above technical problems, which can realize multi-dimensional measurement of the object to be measured.

[0004] In a first aspect, the present application provides a measurement method based on hybrid frequency modulation, which is applied to a measurement system based on hybrid frequency modulation, the system comprising: a first modulator, a second modulator and a light source; the method comprising:

[0005] Interfering the first modulated signal with the positive and negative swept-frequency sideband components of the reflected signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0006] The second modulation signal is interfered with the zero-frequency component of the reflection signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0007] In one embodiment, the method further comprises:

[0008] In the first modulator, the output light of the light source is subjected to frequency sweep sideband modulation by a sinusoidal frequency sweep driving signal to obtain the first modulation signal;

[0009] In the second modulator, the output light of the light source is subjected to fixed-frequency frequency shift modulation by a fixed-frequency driving signal to obtain the second modulated signal.

[0010] In one embodiment, the system further comprises: an optical filter; and the method further comprises:

[0011] By using the optical filter, the first interference signal is divided based on a preset wavelength threshold to obtain a first beat frequency interference signal and a second beat frequency interference signal;

[0012] The absolute distance and / or speed information of the target object is determined based on the first beat frequency interference signal and the second beat frequency interference signal.

[0013] In one embodiment, determining the absolute distance and / or speed information of the target object based on the first beat frequency interference signal and the second beat frequency interference signal includes:

[0014] Performing Fourier transform on the first beat frequency interference signal to obtain a first beat frequency of the first beat frequency interference signal; performing Fourier transform on the second beat frequency interference signal to obtain a second beat frequency corresponding to the second beat frequency interference signal;

[0015] Based on the sum of the first beat frequency and the second beat frequency, determine the mean of the first beat frequency and the second beat frequency; based on calculating the difference between the ending sweep frequency of the output light and the starting sweep frequency of the output light, and determining the ratio of the difference to the modulation period of the sinusoidal sweep drive signal as the sweep speed of the output light; based on the ratio of the mean and the sweep speed of the output light, determine the time delay information between the reflected signal and the output light; based on the product of the time delay information and the speed of light, determine the absolute distance of the target object;

[0016] The Doppler shift of the reflected signal is determined based on the difference between the first beat frequency and the second beat frequency; and the speed information of the target object is determined based on the ratio of the product of the Doppler shift and the speed of light to the zero-frequency component.

[0017] In one embodiment, the method further comprises:

[0018] Mixing the second interference signal with the fixed-frequency driving signal to obtain a first mixing signal; mixing the second interference signal with the orthogonal quantity of the fixed-frequency driving signal to obtain a second mixing signal; determining a mixing signal ratio based on a ratio of the first mixing signal to the second mixing signal; performing an inverse tangent process on the mixing signal ratio to obtain a phase change amount of the second interference signal;

[0019] The product value of the phase change amount and the speed of light is calculated, and the ratio of the product value to the frequency of the zero-frequency component is determined as the micro displacement of the target object.

[0020] In one embodiment, the system further comprises: an optical amplifier and a collimator; the method further comprises:

[0021] Inputting the first modulated signal into the optical amplifier, and amplifying the power of the first modulated signal through the optical amplifier to obtain a power-amplified first modulated signal;

[0022] The power-amplified first modulated signal is transmitted to the target object through the collimator, and a reflected signal reflected by the target object is received through the collimator.

[0023] In a second aspect, the present application further provides a measurement system based on hybrid frequency modulation, the system comprising: a first modulator, a second modulator and a light source, wherein:

[0024] The light source is used to output single-frequency continuous output light;

[0025] The first modulator is used to perform swept-frequency sideband modulation on the output light to obtain a first modulation signal, so that the first modulation signal interferes with the positive and negative swept-frequency sideband components of the reflection signal to obtain a first interference signal, and determine the absolute distance and / or speed information of the target object based on the first interference signal; the reflection signal is obtained by the target object reflecting the received first modulation signal;

[0026] The second modulator is used to perform fixed-frequency frequency shift modulation on the output light to obtain a second modulation signal, so that the second modulation signal interferes with the zero-frequency component of the reflected signal to obtain a second interference signal, and the vibration information of the target object is determined based on the second interference signal.

[0027] In a third aspect, the present application further provides a measurement device based on hybrid frequency modulation, comprising:

[0028] a first determination module, configured to interfere the positive and negative swept frequency sideband components of the reflection signal with the first modulation signal to obtain a first interference signal; and determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulation signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflection signal is obtained by the target object reflecting the received first modulation signal;

[0029] The second determination module is used to interfere the second modulation signal with the zero-frequency component of the reflection signal to obtain a second interference signal; determine the vibration information of the target object based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by a second modulator.

[0030] In a fourth aspect, the present application further provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0031] Interfering the first modulated signal with the positive and negative swept-frequency sideband components of the reflected signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0032] The second modulation signal is interfered with the zero-frequency component of the reflection signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0033] In a fifth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0034] Interfering the first modulated signal with the positive and negative swept-frequency sideband components of the reflected signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0035] The second modulation signal is interfered with the zero-frequency component of the reflection signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0036] In a sixth aspect, the present application further provides a computer program product, including a computer program, which implements the following steps when executed by a processor:

[0037] Interfering the first modulated signal with the positive and negative swept-frequency sideband components of the reflected signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0038] The second modulation signal is interfered with the zero-frequency component of the reflection signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0039] The above-mentioned measurement method, system, device, computer equipment, readable storage medium and program product based on mixed frequency modulation respectively modulate the output light of the light source by means of a first modulator and a second modulator to obtain a first modulation signal and a second modulation signal, interfere with the first modulation signal based on the positive and negative frequency scanning sideband components of the reflected signal after scanning the target object by the first modulation signal to obtain a first interference signal, and determine the absolute distance and / or speed information of the target object based on the first interference signal; interfere with the second modulation signal and the zero-frequency component of the reflected signal to obtain a second interference signal, and determine the vibration information of the target object based on the second interference signal, so as to realize multi-dimensional measurement of the target object and improve the measurement efficiency of the target object. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0041] FIG1 is a schematic diagram of the structure of a measurement system based on hybrid frequency modulation in one embodiment;

[0042] FIG2 is a schematic flow chart of a measurement method based on mixed frequency modulation in one embodiment;

[0043] FIG3 is a schematic diagram of frequency distribution of a signal in one embodiment;

[0044] FIG4 is a schematic diagram of the structure of a signal processing device in one embodiment;

[0045] FIG5 is a block diagram of a measurement device based on hybrid frequency modulation in one embodiment;

[0046] FIG. 6 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] The measurement method based on hybrid frequency modulation provided in the embodiment of the present application can be applied to the system shown in Figure 1. The measurement system based on hybrid frequency modulation includes: a light source, a first coupler, a first modulator, a second modulator, a second coupler, a third coupler, an optical amplifier, a circulator, a collimator, a fourth coupler, a fifth coupler, an optical filter, a first detector, a second detector, a third detector and a signal processing device.

[0049] The light source may be a single-frequency semiconductor laser, which is used to output single-frequency continuous output light. The output light of the light source passes through a first coupler, which includes a first output end and a second output end, the first output end is connected to a first modulator, and the second output end is connected to a second modulator. The output light of the light source is input to the first modulator through the first output end of the first coupler, and the output light of the light source is input to the second modulator through the second output end of the first coupler.

[0050] The first modulator performs swept-sideband modulation on the received output light to obtain a first modulated signal, and inputs the first modulated signal into the second coupler. The second coupler includes a first output end and a second output end, the first output end is connected to the optical amplifier, and the second output end is connected to the third coupler, the first modulated signal is input into the optical amplifier through the first output end of the second coupler, and the first modulated signal is input into the third coupler through the second output end of the second coupler.

[0051] The optical amplifier is used to amplify the power of the first modulated signal and input the amplified first modulated signal into the circulator.

[0052] A circulator is used to realize unidirectional transmission of optical path signals. The circulator includes a first end, a second end and a third end. If the first end of the circulator is an input end, the second end is used as an output end; if the second end of the circulator is an input end, the third end is used as an output end. The first end is used to receive the first modulated signal after amplification of power and send it to the collimator through the second end.

[0053] The collimator sends the amplified first modulated signal to the target object and receives the reflected signal reflected by the target object. The collimator sends the received reflected signal to the second end of the circulator. The circulator inputs the received reflected signal to the fourth coupler through the third end of the circulator.

[0054] The fourth coupler includes a first output end and a second output end, the first output end of the fourth coupler is connected to the third coupler, and the second output end of the fourth coupler is connected to the fifth coupler. The reflected signal is input to the third coupler through the first output end, and the reflected signal is input to the fifth coupler through the second output end. In the third coupler, the positive and negative swept frequency sideband components of the first modulated signal are interfered with the positive and negative swept frequency sideband components of the reflected signal to obtain a first interference signal, and the first interference signal is input to the optical filter.

[0055] There are transmission spectrum and reflection spectrum in the optical filter, which can make the positive sideband in the transmission spectrum and the negative sideband in the reflection spectrum. The positive sideband in the transmission spectrum is filtered out through the passband, and the negative sideband in the reflection spectrum is filtered out through the stopband. The optical filter uses the transmission spectrum and the reflection spectrum to filter the first interference signal to obtain the first beat frequency interference signal and the second beat frequency interference signal. The wavelength of the first beat frequency interference signal is in the transmission spectrum of the optical filter, and the wavelength division of the second beat frequency interference signal is in the reflection spectrum of the optical filter. The optical filter includes a first output end and a second output end. The first beat frequency interference signal is sent to the first detector through the first output end of the optical filter, and the first beat frequency interference signal is sent to the second detector through the second output end of the optical filter.

[0056] In the second modulator, the output light of the light source is subjected to fixed-frequency frequency shift modulation to obtain a second modulation signal, and the second modulation signal is sent to the fifth coupler. In the fifth coupler, the second modulation signal and the zero-frequency component of the reflected signal are interfered to obtain a second interference signal, and the second interference signal is sent to the third detector.

[0057] The signal processing device receives the first beat frequency interference signal of the first detector and the second beat frequency interference signal of the second detector respectively, and performs signal processing on the first beat frequency interference signal and the second beat frequency interference signal respectively to obtain the absolute distance and speed information of the target object. The signal processing device receives the second interference signal of the third detector, performs signal processing on the second interference signal, and obtains the vibration information of the target object. The specific signal processing process will be described in detail in the subsequent embodiments and will not be repeated here.

[0058] The system has good detection accuracy and can measure absolute distance, speed information and vibration information with a single light source. At the same time, the optical signal of the system passes through the same device, optical fiber and space link during transmission, realizing common path detection, which maximizes the consistency of measurement and the accuracy of environmental interference compensation.

[0059] In an exemplary embodiment, as shown in FIG2 , a measurement method based on hybrid frequency modulation is provided, which is described by applying the method to the measurement system based on hybrid frequency modulation in FIG1 , and includes the following steps. Among them:

[0060] Step 201: interfere a first modulated signal with positive and negative swept frequency sideband components of a reflected signal to obtain a first interference signal; and determine the absolute distance and / or speed information of a target object based on the first interference signal.

[0061] The first modulation signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator. The first modulator may be an electro-optical modulator. The reflected signal is obtained by the target object reflecting the received first modulation signal. The positive and negative swept-frequency sideband components include positive sidebands and negative sidebands. The signal with a wavelength greater than a preset wavelength threshold in the first modulation signal is a positive sideband, and the signal with a wavelength less than the preset wavelength threshold is a negative sideband. The preset wavelength threshold may be a wavelength corresponding to a zero-frequency component. The wavelength corresponding to the zero-frequency component may be a wavelength of the output light of the light source.

[0062] Specifically, in the third coupler, the positive and negative swept frequency sideband components of the first modulated signal are interfered with the positive and negative swept frequency sideband components of the reflected signal to obtain a first interference signal. In the optical filter, the first interference signal is filtered to obtain a filtered first interference signal. The signal processing device demodulates the filtered first interference signal to obtain a demodulation result, and determines the absolute distance of the target object based on the demodulation result, or demodulates the filtered first interference signal to obtain a demodulation result, and determines the speed of the target object based on the demodulation result, or demodulates the first interference signal after the wave to obtain a demodulation result, and determines the absolute distance and speed of the target object based on the demodulation result.

[0063] Step 202: interfere the second modulated signal with the zero-frequency component of the reflected signal to obtain a second interference signal; and determine the vibration information of the target object based on the second interference signal.

[0064] The second modulation signal may be obtained by performing fixed-frequency frequency shift modulation on the output light by a second modulator. The second modulator may be an acousto-optic modulator. Fixed-frequency frequency shift modulation may change the frequency of the output light of the light source.

[0065] Specifically, in the fifth coupler, the frequency shift component corresponding to the second modulated signal interferes with the zero-frequency component of the reflected signal to obtain a second interference signal. The signal processing device demodulates the first interference signal to obtain a phase change caused by the vibration of the target object, and determines the vibration information of the object based on the phase change.

[0066] In the above-mentioned measurement method based on mixed frequency modulation, the output light of the light source is modulated by the first modulator and the second modulator respectively to obtain the first modulation signal and the second modulation signal. The positive and negative frequency scanning sideband components of the reflected signal after scanning the target object based on the first modulation signal interfere with the first modulation signal to obtain the first interference signal, and the absolute distance and / or speed information of the target object is determined based on the first interference signal; the second modulation signal interferes with the zero-frequency component of the reflected signal to obtain the second interference signal, and the vibration information of the target object is determined based on the second interference signal, which can realize multi-dimensional measurement of the target object and improve the measurement efficiency of the target object.

[0067] In an exemplary embodiment, the measurement method based on hybrid frequency modulation further includes:

[0068] In the first modulator, the output light of the light source is subjected to swept frequency sideband modulation by a sinusoidal swept frequency driving signal to obtain a first modulation signal; in the second modulator, the output light of the light source is subjected to fixed frequency shift frequency modulation by a fixed frequency driving signal to obtain a second modulation signal.

[0069] Specifically, the first coupler includes a first output end and a second output end, the first output end is connected to the first modulator, and the second output end is connected to the second modulator, based on this, the output light of the light source is input to the first modulator through the first output end, and the output light of the light source is input to the second modulator through the second output end; in this way, the first modulator receives the output light of the light source, and uses a sinusoidal swept frequency drive signal to perform swept frequency sideband modulation on the output light of the light source to obtain a second modulated signal. The specific processing process of the output light of the light source by the second modulator will be described in detail in subsequent embodiments and will not be repeated here. Exemplarily, a sinusoidal swept frequency drive signal is input to the first modulator, and in the first modulator, the output light of the light source is sideband modulated using the sinusoidal swept frequency drive signal to obtain a first modulated signal. Among them, the sinusoidal swept frequency drive signal can be expressed by the following formula:

[0070]

[0071]

[0072]

[0073] Among them, V I is the in-phase signal of the orthogonal voltage; V P is the amplitude of the sinusoidal swept frequency driving signal; f RF is the frequency of the sine sweep driving signal; V Q is the orthogonal signal of the orthogonal voltage; f1 is the starting sweep frequency of the output light; f2 is the ending sweep frequency of the output light; and T is the modulation period of the sinusoidal sweep drive signal.

[0074] Specifically, the second modulator receives the output light of the light source, and uses the fixed frequency driving signal to perform fixed frequency shift frequency modulation on the frequency of the output light of the light source to obtain a second modulated signal. Exemplarily, when the fixed frequency driving signal is a sinusoidal signal with a frequency of (Ω1-Ω2), the frequency of the output light of the light source changes to f after passing through the second modulator. c +Ω2-Ω1, that is, the frequency of the second modulation signal is f c +Ω2-Ω1. Among them, f c is the frequency of the zero-frequency component.

[0075] In this embodiment, the output light of the light source is modulated in the first modulator and the second modulator respectively to obtain corresponding modulation signals for subsequent detection of reflected light of the target object, so as to facilitate detection of the target object from multiple dimensions.

[0076] In an exemplary embodiment, the measurement method based on hybrid frequency modulation further includes:

[0077] The first interference signal is divided by an optical filter based on a preset wavelength threshold to obtain a first beat frequency interference signal and a second beat frequency interference signal; the absolute distance and / or speed information of the target object is determined based on the first beat frequency interference signal and the second beat frequency interference signal.

[0078] The preset wavelength threshold is determined according to a threshold that divides the optical filter into two ranges: a transmission spectrum and a reflection spectrum.

[0079] Specifically, the optical filter can divide the first interference signal based on the wavelength division multiplexing method, and the first interference signal can be divided using the transmission spectrum and the reflection spectrum. For example, the signal in the transmission band of the first interference signal can be retained to obtain the first beat frequency interference signal. For example, the signal in the first interference signal that is greater than the preset wavelength can be determined as the signal in the transmission band, and the signal in the transmission band is determined as the first beat frequency interference signal; the interference signal in the first interference signal that is less than the preset wavelength threshold can be reflected by the reflection spectrum to obtain the second beat frequency interference signal. It should be understood that the "first" and "second" here are only used to distinguish interference signals in different wavelength ranges, and are not limited here.

[0080] Specifically, the first beat frequency interference signal is received by the first detector, and the second beat frequency interference signal is received by the second detector. The signal processing device receives the first beat frequency interference signal from the first detector and receives the second beat frequency interference signal from the second detector. The first beat frequency interference signal and the second beat frequency interference signal are demodulated in the signal processing device respectively. The signal processing device demodulates the first beat frequency interference signal to obtain a demodulation result, and determines the absolute distance of the target object based on the demodulation result, or demodulates the first beat frequency interference signal to obtain a demodulation result, and determines the speed of the target object based on the demodulation result, or demodulates the first beat frequency interference signal to obtain a demodulation result, and determines the absolute distance and speed of the target object based on the demodulation result.

[0081] Exemplarily, the first beat frequency interference signal can be expressed by the following formula:

[0082]

[0083] Among them, I SM1 (t) is the first beat frequency interference signal; A SM1 is the amplitude of the first beat frequency interference signal; τ is the time delay information between the reflected signal and the output light; f p is the first beat frequency; φ SM1 is the initial phase of the first beat frequency interference signal.

[0084] The second beat frequency interference signal can be expressed by the following formula:

[0085]

[0086] Among them, I SM2 (t) is the second beat frequency interference signal; A SM2 is the amplitude of the second beat frequency interference signal; f n is the second beat frequency; φ SM2 is the initial phase of the second beat frequency interference signal.

[0087] In this embodiment, the optical filter obtains a first beat frequency interference signal and a second beat frequency interference signal by performing wavelength division multiplexing processing on the first interference signal. The signal processing device can realize independent demodulation of the positive sideband and the negative sideband of the interference signal, so that the Doppler frequency shift caused by environmental disturbances can be eliminated, thereby improving the measurement accuracy of the absolute distance and velocity information of the swept frequency.

[0088] In an exemplary embodiment, determining the absolute distance and / or speed information of the target object based on the first beat frequency interference signal and the second beat frequency interference signal includes:

[0089] Performing Fourier transform on the first beat frequency interference signal to obtain the first beat frequency of the first beat frequency interference signal; performing Fourier transform on the second beat frequency interference signal to obtain the second beat frequency corresponding to the second beat frequency interference signal; determining the mean of the first beat frequency and the second beat frequency based on the sum of the first beat frequency and the second beat frequency; determining the sweep speed of the output light based on the difference between the calculated ending sweep frequency of the output light and the starting sweep frequency of the output light and the ratio of the difference to the modulation period of the sinusoidal sweep drive signal; determining the time delay information between the reflected signal and the output light based on the ratio of the mean value and the sweep speed of the output light; determining the absolute distance of the target object based on the product of the time delay information and the speed of light; determining the Doppler shift of the reflected signal based on the difference between the first beat frequency and the second beat frequency; determining the speed information of the target object based on the ratio of the product of the Doppler shift and the speed of light to the zero-frequency component.

[0090] Specifically, since the target object may generate Doppler frequency shift due to the environment or velocity disturbance, the frequency distribution of the reflected signal may be affected during the detection process.

[0091] As shown in FIG3 , FIG3 is a schematic diagram of the frequency distribution of a signal in an embodiment, wherein the ordinate in FIG3 represents the light frequency / beat frequency, and the abscissa represents time. The thick solid line in the figure is a schematic diagram of the frequency distribution of the output light. The thick dashed line in FIG3 is the frequency distribution of the reflected signal of the target object in a dynamic state, and the dot-dash line is the frequency distribution of the reflected signal of the target object in a static state. 1 / 2 of the difference in the beat frequency between the thick dashed line and the dot-dash line is the Doppler shift frequency f d As shown in Figure 3, the frequency distribution of the positive sideband and the negative sideband is symmetrical about the carrier frequency (zero frequency component frequency), and the optical frequency value is greater than f c The frequency signal is a negative sideband, and the optical frequency value is less than f c The frequency signal is the positive sideband.

[0092] Specifically, the signal processing device performs Fourier transform on the first beat frequency interference signal to obtain the first beat frequency of the first beat frequency interference signal; and performs Fourier transform on the second beat frequency interference signal to obtain the second beat frequency corresponding to the second beat frequency interference signal. As shown in FIG3, the double dashed line represents the beat frequency f of the positive sideband. p Distribution, f p Corresponding to the difference between the frequency of the target object in motion and the frequency of the output light under the positive sideband component, the double solid line represents the beat frequency f of the negative sideband n Distribution, f n Corresponding to the difference between the frequency of the target object when it is moving and the frequency of the output light under the negative sideband component.

[0093] Specifically, the signal processing device can calculate the sum of the first beat frequency and the second beat frequency, and obtain the mean of the first beat frequency and the second beat frequency based on the sum of the first beat frequency and the second beat frequency divided by 2. The signal processing device can determine the time delay information τ between the reflected signal and the output light based on the difference between the end sweep frequency f2 of the output light and the start sweep frequency f1 of the output light, and the ratio of the modulation period of the sinusoidal sweep drive signal, and determine the absolute distance of the target object based on 1 / 2 of the product value of the time delay information and the speed of light. For example, the absolute distance of the target object can be calculated by the following formula:

[0094]

[0095] Where R is the absolute distance of the target object; c is the speed of light.

[0096] The signal processing device determines the Doppler shift of the reflected signal based on 1 / 2 of the difference between the first beat frequency and the second beat frequency; and determines the speed information of the target object based on the ratio of the product of the Doppler shift and the speed of light to the zero-frequency component. For example, the absolute distance of the target object can be calculated by the following formula:

[0097]

[0098] Among them, v is the velocity information of the target object.

[0099] In an exemplary embodiment, the measurement method based on hybrid frequency modulation further includes:

[0100] The second interference signal is mixed with the fixed-frequency driving signal to obtain the first mixing signal; the second interference signal is mixed with the orthogonal quantity of the fixed-frequency driving signal to obtain the second mixing signal; the ratio of the first mixing signal to the second mixing signal is processed by inverse tangent to obtain the phase change of the second interference signal; the product value of the phase change and the speed of light is calculated, and the ratio of the product value to the frequency of the zero-frequency component is determined as the small displacement of the target object.

[0101] Among them, the micro displacement refers to the displacement of the target object less than 100 microns during the measurement process.

[0102] Specifically, in the signal processing device, the second interference signal is converted into a current signal to obtain a first current signal and a second current signal, and the first interference signal is mixed with the drive signal of the acousto-optic modulator and the first current signal to obtain a first mixed signal. The second interference signal is mixed with the orthogonal quantity corresponding to the drive signal to obtain a second mixed signal, and further an in-phase / quadrature (I / Q) signal is obtained through a low-pass filter in the signal processing device, and the I / Q signal is subjected to inverse tangent processing to obtain a phase change of the second interference signal. The phase change information and the ratio of the speed of light to the frequency of the zero-frequency component are used as the vibration information of the target object.

[0103] Specifically, when the fixed-frequency driving signal is a sinusoidal signal with a frequency of (Ω1-Ω2), the output light of the light source changes its frequency to f after passing through the second modulator. c +Ω2-Ω1, that is, the frequency of the second modulation signal is f c +Ω2-Ω1. The second interference signal can be expressed by the following formula:

[0104]

[0105] Among them, I FM (t) is the second interference signal; A FM is the amplitude of the second interference signal; φ FM is the initial phase of the second interference signal; It is the phase change introduced by the vibration of the target object.

[0106] The signal processing device can obtain the tiny vibration information of the object by demodulating the phase change of the fixed-frequency modulated second interference signal.

[0107] According to the Doppler effect, a small vibration or velocity disturbance of a target object will produce a Doppler frequency shift, which is calculated using the following formula:

[0108]

[0109] The Doppler frequency shift will cause a phase change. The second interference signal is mixed with the fixed-frequency drive signal and the orthogonal amount of the fixed-frequency drive signal to obtain the phase change of the second interference signal, which is the integral of the Doppler frequency shift in the demodulation interval. The phase change is calculated by the following formula:

[0110]

[0111] Based on this, the signal processing device can determine the vibration information of the target object according to the phase change and the ratio of the speed of light to the frequency of the zero-frequency component. The vibration information of the target object is calculated by the following formula:

[0112]

[0113] in, It is the vibration information of the target object.

[0114] In this embodiment, since the resolution of the swept frequency absolute distance measurement is generally in the millimeter level, it is difficult to demodulate the micron-level vibration. However, the frequency-shift optical interference under fixed frequency modulation solves this problem well, and also reflects the advantages of the measurement system based on fusion modulation, which can effectively reduce the influence of noise on signal phase demodulation and realize the measurement of the micro vibration of the target object.

[0115] In an exemplary embodiment, the measurement method based on hybrid frequency modulation further includes:

[0116] The first modulated signal is input into an optical amplifier, and the power of the first modulated signal is amplified by the optical amplifier to obtain a power-amplified first modulated signal; the power-amplified first modulated signal is transmitted to a target object through a collimator, and a reflected signal reflected by the target object is received through the collimator.

[0117] The optical amplifier is used to amplify the power of the first modulated signal.

[0118] Specifically, the optical amplifier receives the first modulated signal sent by the first modulator, amplifies the power of the first modulated signal, and obtains the first modulated signal after the power is amplified. The circulator receives the first modulated signal after the power is amplified, and sends the signal to the collimator, and the collimator transmits the signal to the target object. The target object reflects the signal to the collimator, and the collimator receives the reflected light of the target object and transmits the reflected light to the circulator. The circulator transmits the reflected light to the fourth coupler for subsequent processing as described in the above embodiment. In this embodiment, the method realizes common-path detection and maximizes the accuracy of measurement.

[0119] In one embodiment, as shown in Figure 4, Figure 4 is a structural schematic diagram of a signal processing device in an example, and the signal processing module includes a first signal processing unit, a second signal processing unit, a high-pass filtering unit, a spectrum processing unit, a third signal processing unit, a signal mixing unit, a low-pass filtering unit, a phase processing unit, a calculation module, and a display module.

[0120] The first signal processing unit is used to receive a first beat frequency interference signal. The second signal processing unit is used to receive a second beat frequency interference signal. In the high-pass filter unit, the first beat frequency interference signal is high-pass filtered to obtain a filtered first beat frequency interference signal, and the second beat frequency interference signal is high-pass filtered to obtain a filtered second beat frequency interference signal. In the spectrum processing unit, the filtered first beat frequency interference signal and the filtered second beat frequency interference signal are Fourier processed to obtain a first beat frequency and a second beat frequency. In the calculation module, calculation processing is performed based on the first beat frequency and the second beat frequency, and the absolute distance and speed of the target object are determined according to the calculation results.

[0121] The third signal processing unit is used to receive the second interference signal, and convert the second interference signal into a current signal, and divide the current signal into a first current signal and a second current signal. In the signal mixing unit, the first interference signal is mixed with the drive signal of the acousto-optic modulator and the first current signal to obtain a first mixed signal. The second interference signal is mixed with the orthogonal quantity corresponding to the drive signal to obtain a second mixed signal. In the low-pass filtering unit, the first mixed signal is low-pass filtered to obtain an in-phase I signal, and the second mixed signal is low-pass filtered to obtain an orthogonal Q signal. In the phase processing module, the I / Q signal is processed by inverse tangent to obtain a phase change. In the calculation module, the small vibration of the target object is determined based on the phase change.

[0122] The display module can display information such as the absolute distance, speed, and tiny vibration of the target object.

[0123] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0124] Based on the same inventive concept, the embodiment of the present application also provides a measurement device based on mixed frequency modulation for implementing the measurement method based on mixed frequency modulation involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more embodiments of the measurement device based on mixed frequency modulation provided below can refer to the limitations of the measurement method based on mixed frequency modulation above, and will not be repeated here.

[0125] In an exemplary embodiment, as shown in FIG5 , a measurement device based on hybrid frequency modulation is provided. The measurement device 50 based on hybrid frequency modulation includes: a first determination module 51 and a second determination module 52, wherein:

[0126] The first determination module 51 is used to interfere the positive and negative swept frequency sideband components of the reflection signal with the first modulation signal to obtain a first interference signal; determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulation signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflection signal is obtained by the target object reflecting the received first modulation signal;

[0127] The second determination module 52 is used to interfere the second modulation signal with the zero-frequency component of the reflection signal to obtain a second interference signal; determine the vibration information of the target object based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0128] In one example, the modulation module is used to perform frequency sweeping sideband modulation on the output light of the light source by a sinusoidal frequency sweeping driving signal in a first modulator to obtain a first modulation signal;

[0129] In the second modulator, the output light of the light source is subjected to fixed-frequency frequency shift modulation by a fixed-frequency driving signal to obtain a second modulated signal.

[0130] In one example, the first determination module 51 is further used to divide the first interference signal based on a preset wavelength threshold through an optical filter to obtain a first beat frequency interference signal and a second beat frequency interference signal;

[0131] The absolute distance and / or speed information of the target object is determined based on the first beat frequency interference signal and the second beat frequency interference signal.

[0132] In one example, the first determination module 51 is further used to perform Fourier transform on the first beat frequency interference signal to obtain a first beat frequency of the first beat frequency interference signal; perform Fourier transform on the second beat frequency interference signal to obtain a second beat frequency corresponding to the second beat frequency interference signal;

[0133] Based on the sum of the first beat frequency and the second beat frequency, the mean of the first beat frequency and the second beat frequency is determined; based on the difference between the ending sweep frequency of the output light and the starting sweep frequency of the output light, the ratio of the difference to the modulation period of the sinusoidal sweep drive signal is determined as the sweep speed of the output light; based on the ratio of the mean and the sweep speed of the output light, the time delay information between the reflected signal and the output light is determined; based on the product of the time delay information and the speed of light, the absolute distance of the target object is determined;

[0134] The Doppler shift of the reflected signal is determined based on the difference between the first beat frequency and the second beat frequency; and the speed information of the target object is determined based on the ratio of the product of the Doppler shift and the speed of light to the zero-frequency component.

[0135] In one example, the second determining module 52 is further configured to

[0136] The second interference signal is mixed with the fixed-frequency driving signal to obtain a first mixing signal; the second interference signal is mixed with the orthogonal quantity of the fixed-frequency driving signal to obtain a second mixing signal; the ratio of the first mixing signal to the second mixing signal is processed by an inverse tangent to obtain a phase change of the second interference signal;

[0137] The product of the phase change and the speed of light is calculated, and the ratio of the product to the frequency of the zero-frequency component is determined as the tiny displacement of the target object.

[0138] In one example, the transmitting module is used to input the first modulated signal into the optical amplifier, and amplify the power of the first modulated signal through the optical amplifier to obtain the power-amplified first modulated signal;

[0139] The power-amplified first modulated signal is transmitted to the target object through the collimator, and the reflected signal reflected by the target object is received through the collimator.

[0140] Each module in the above-mentioned measurement device based on hybrid frequency modulation can be implemented in whole or in part by software, hardware and a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each module above.

[0141] In an exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be shown in FIG6. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store a first interference signal and a second interference signal. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a measurement method based on mixed frequency modulation is implemented.

[0142] Those skilled in the art will understand that the structure shown in FIG. 6 is merely a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0143] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0144] Interfere the first modulated signal with the positive and negative swept frequency sideband components of the reflected signal to obtain a first interference signal; determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0145] The second modulation signal is interfered with the zero-frequency component of the reflected signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0146] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0147] Interfere the first modulated signal with the positive and negative swept frequency sideband components of the reflected signal to obtain a first interference signal; determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0148] The second modulation signal is interfered with the zero-frequency component of the reflected signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0149] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0150] Interfere the first modulated signal with the positive and negative swept frequency sideband components of the reflected signal to obtain a first interference signal; determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal;

[0151] The second modulation signal is interfered with the zero-frequency component of the reflected signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

[0152] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0153] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0154] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A measurement method based on hybrid frequency modulation, characterized in that: Applied to a measurement system based on hybrid frequency modulation, the system comprises: a first modulator, a second modulator and a light source; the method comprises: Interfering the first modulated signal with the positive and negative swept-frequency sideband components of the reflected signal to obtain a first interference signal; determining the absolute distance and / or speed information of the target object based on the first interference signal; the first modulated signal is obtained by performing swept-frequency sideband modulation on the output light of the light source by the first modulator, and the reflected signal is obtained by the target object reflecting the received first modulated signal; The second modulation signal is interfered with the zero-frequency component of the reflection signal to obtain a second interference signal; the vibration information of the target object is determined based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by the second modulator.

2. The method according to claim 1, characterized in that: The method further comprises: In the first modulator, the output light of the light source is subjected to frequency sweep sideband modulation by a sinusoidal frequency sweep driving signal to obtain the first modulation signal; In the second modulator, the output light of the light source is subjected to fixed-frequency frequency shift modulation by a fixed-frequency driving signal to obtain the second modulated signal.

3. The method according to claim 1, characterized in that The system further comprises: an optical filter; and the method further comprises: By using the optical filter, the first interference signal is divided based on a preset wavelength threshold to obtain a first beat frequency interference signal and a second beat frequency interference signal; The absolute distance and / or speed information of the target object is determined based on the first beat frequency interference signal and the second beat frequency interference signal.

4. The method according to claim 3, characterized in that: The determining the absolute distance and / or speed information of the target object based on the first beat frequency interference signal and the second beat frequency interference signal includes: Performing Fourier transform on the first beat frequency interference signal to obtain a first beat frequency of the first beat frequency interference signal; performing Fourier transform on the second beat frequency interference signal to obtain a second beat frequency corresponding to the second beat frequency interference signal; Based on the sum of the first beat frequency and the second beat frequency, determine the mean of the first beat frequency and the second beat frequency; based on calculating the difference between the ending sweep frequency of the output light and the starting sweep frequency of the output light, and determining the ratio of the difference to the modulation period of the sinusoidal sweep drive signal as the sweep speed of the output light; based on the ratio of the mean and the sweep speed of the output light, determine the time delay information between the reflection signal and the output light; based on the product of the time delay information and the speed of light, determine the absolute distance of the target object; The Doppler shift of the reflected signal is determined based on the difference between the first beat frequency and the second beat frequency; and the speed information of the target object is determined based on the ratio of the product of the Doppler shift and the speed of light to the zero-frequency component.

5. The method according to claim 2, characterized in that: The method further comprises: Mixing the second interference signal with the fixed-frequency driving signal to obtain a first mixing signal; mixing the second interference signal with the orthogonal quantity of the fixed-frequency driving signal to obtain a second mixing signal; performing arc tangent processing on the ratio of the first mixing signal to the second mixing signal to obtain a phase change amount of the second interference signal; The product value of the phase change amount and the speed of light is calculated, and the ratio of the product value to the frequency of the zero-frequency component is determined as the micro displacement of the target object.

6. The method according to claim 1, characterized in that The system further comprises: an optical amplifier and a collimating lens; the method further comprises: Inputting the first modulated signal into the optical amplifier, and amplifying the power of the first modulated signal through the optical amplifier to obtain a power-amplified first modulated signal; The power-amplified first modulated signal is transmitted to the target object through the collimator, and a reflected signal reflected by the target object is received through the collimator.

7. A measurement system based on hybrid frequency modulation, characterized in that: The system comprises: a first modulator, a second modulator and a light source, wherein: The light source is used to output single-frequency continuous output light; The first modulator is used to perform swept-frequency sideband modulation on the output light to obtain a first modulation signal, so that the first modulation signal interferes with the positive and negative swept-frequency sideband components of the reflection signal to obtain a first interference signal, and determine the absolute distance and / or speed information of the target object based on the first interference signal; the reflection signal is obtained by the target object reflecting the received first modulation signal; The second modulator is used to perform fixed-frequency frequency shift modulation on the output light to obtain a second modulation signal, so that the second modulation signal interferes with the zero-frequency component of the reflected signal to obtain a second interference signal, and the vibration information of the target object is determined based on the second interference signal.

8. A measurement device based on hybrid frequency modulation, characterized in that: The device comprises: a first determination module, configured to interfere the positive and negative swept frequency sideband components of the reflection signal with the first modulation signal to obtain a first interference signal; and determine the absolute distance and / or speed information of the target object based on the first interference signal; the first modulation signal is obtained by performing swept frequency sideband modulation on the output light of the light source by the first modulator, and the reflection signal is obtained by the target object reflecting the received first modulation signal; The second determination module is used to interfere the second modulation signal with the zero-frequency component of the reflection signal to obtain a second interference signal; determine the vibration information of the target object based on the second interference signal; the second modulation signal is obtained by performing fixed-frequency shift frequency modulation on the output light by a second modulator.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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