A structure doppler velocimeter

Abstract

The application discloses a kind of structural doppler velocimeters, belong to optical measurement field.The velocimeter utilizes structural light technology and combines with doppler velocity measurement, for accurately measuring the speed of target object.The velocimeter includes light source module, light field modulation module, signal detection module.Light field modulation module can synthesize the light beam with specific radial wave vector and amplitude phase distribution, output structural light.The motion target to be measured and structural light interact and reflect structural doppler signal, signal detection module receives echo structural doppler signal, and signal is analyzed and handled, whereby the accurate measurement of target object speed can be realized.The structural doppler velocimeter of the application has the advantages of simple structure, convenient operation, wide application range.It has wide application prospect in the fields of industrial automation, fluid dynamics research, biomedical engineering, etc., fills the gap of existing technology in non-zero difference doppler signal detection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical measurement, and more particularly, relates to a structured Doppler velocimeter. BACKGROUND

[0002] It is well known that Doppler effect is caused by the relative motion between the wave source and the observer, which has a wide range of applications in the field of optical and acoustic measurement. The Doppler velocimetry based on Doppler effect generally has the advantages of high spatial resolution, wide measurement range, non-contact, etc. In the long history of the development of Doppler effect, researchers often focus on the frequency change of the light field in the interaction with the object. Recently, with the exploration of the dimension of light field by researchers, a novel structured Doppler effect based on structured light field with radial wave vector component is revealed and verified. As a new extension of the traditional Doppler effect, the structured Doppler effect provides a new way for the acquisition of the velocity of the moving target and breaks the dependence on the configuration of the reference light path in the traditional Doppler velocimetry. Generally, the photodetector cannot directly detect the optical frequency domain, but can only measure the beat frequency between two light beams to obtain the frequency change before and after the interaction of the light beam with the moving object, so that two light beams are needed to form a homodyne interference in most applications of the traditional Doppler effect. For the general velocimetry scheme with reference light path configuration, the system itself has poor resistance to the influence of environmental interference due to the difference in optical path. It can be seen that the homodyne interference structure of the traditional Doppler velocimetry system has room for optimization in order to adapt to various forms of motion and complex detection scenes. Considering the method based on structured Doppler effect, the back Doppler signal detected by the single beam structured light can be directly detected without the need for an additional reference light path, which has strong anti-environmental interference ability and simple optical path structure. Among them, the superposition of light with different radial wave vector components forms a single beam of detection light, the detection light interacts with the moving target, and the frequency shift carried by the back signal light is positively correlated with the size of the velocity of the moving target along the optical axis. Therefore, based on the structured Doppler effect, a non-homodyne Doppler signal detection velocimetry method for the moving target can be found. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a structured Doppler velocimeter, which aims to break through the limitation of the traditional scheme in setting up a homodyne interference process in the Doppler velocimetry system, and to measure the velocity of the moving target by using single beam light detection and direct detection of the signal light based on the novel structured Doppler effect, thereby filling the gap in the related art.

[0004] To achieve the above-mentioned purpose, according to the present application, a structured Doppler velocimeter is provided, which comprises: a light source module, a light field modulation module, a signal detection module,

[0005] The light source module is used to emit a Gaussian light beam, the Gaussian light beam passes through the light field modulation module to generate a specific structured light carrying a transverse wave vector component, the structured light has a phase lag effect and contains two different radial angular spectrum distributions; the structured light field is incident to a to-be-measured moving target, and a generated echo Doppler signal is received by the signal detection module, the signal detection module is used for data processing and analysis on the received Doppler signal, and the moving speed of the to-be-measured moving target is calculated.

[0006] Preferably, the structured light with the transverse wave vector has a phase lag effect and contains two different radial angular spectrum distributions, the propagation time delay of the light field is regulated by designing the radial angular spectrum distribution of the structured light, and the two different radial angular spectrum distributions can control the longitudinal propagation factor of the light field and induce a Doppler beat frequency.

[0007] Preferably, the light field modulation module includes a polarizer, a half-wave plate, a first beam splitter, a spatial light modulator, a first lens, an aperture, a second lens, and a second beam splitter; the Gaussian light beam emitted by the light source module passes through the polarizer to be adjusted into linearly polarized Gaussian light, the linearly polarized Gaussian light passes through the half-wave plate to adjust the polarization direction and is converted into linearly polarized Gaussian light corresponding to the optimal polarization direction of the spatial light modulator, the linearly polarized Gaussian light passes through the first beam splitter and is modulated by the spatial light modulator to obtain structured light, the structured light is reflected by the first beam splitter and passes through a 4-f optical system composed of the first lens, the aperture, and the second lens to filter out the first diffraction order, the filtered structured light is incident to a to-be-measured moving object through the second beam splitter, and a returned echo Doppler signal is reflected by the second beam splitter to the signal detection module.

[0008] Preferably, the spatial light modulator can also be replaced by a digital micromirror array or a specially designed conical lens, so as to generate a structured light field with a specific radial wave vector, generate and superimpose different modes to synthesize a single-beam structured light transmitted coaxially.

[0009] Preferably, when the surface of the to-be-measured moving target is a mirror surface, the signal detection module includes an aperture and a photodetector, the aperture is a centrally placed slit or an off-axis placed aperture, and the photodetector is placed behind the aperture to locally receive the echo Doppler signal and perform Fourier analysis on the signal to extract the speed information of the moving target.

[0010] Preferably, the linearly polarized Gaussian light passes through the first beam splitter and is modulated by the spatial light modulator to obtain structured light, the structured light is superimposed by Bessel light and Gaussian light, and the calculated speed of the to-be-measured moving target is v=c|Δf| / α 2 f0. Wherein, f0 is the base frequency of the Bessel light and the Gaussian light, v is the speed of the to-be-measured target along the optical axis direction, c is the speed of light, |Δf| is the detected frequency peak value, and α is the ratio of the radial wave vector of the Bessel light to the global wave vector.

[0011] Preferably, the linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is superimposed by two different radial wave vectors of Bessel light, and the speed of the moving target is calculated: Wherein, f0 is the base frequency of the two Bessel lights, v is the speed of the target to be measured along the optical axis, c is the speed of light, |Δf| is the detected frequency peak, α1 is the ratio of the radial wave vector of the first Bessel light to the global wave vector, and α2 is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

[0012] Preferably, when the surface of the moving target to be measured is a mirror surface, the signal detection module is a camera, the camera is placed at the detection end to directly receive the echo Doppler signal, the rotational angular velocity of the signal light spot is observed by the camera, the speed of the moving target is inferred according to the size of the rotational angular velocity, and the direction of the speed of the moving target is inferred according to the direction of the rotational angular velocity.

[0013] Preferably, the linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is superimposed by two different radial wave vectors of high-order Bessel light, and the speed of the moving target is calculated: v=Ω·cΔl / 2πf0Δα 2 . Wherein, f0 is the base frequency of the two Bessel lights, v is the speed of the target to be measured along the optical axis, c is the speed of light, Ω is the rotational speed of the light spot, Δα is the square difference of the ratio of the radial wave vector of the two high-order Bessel lights to the global wave vector, and Δl=l1-l2 is the difference between the topological charges of the two high-order Bessel lights.

[0014] Preferably, when the surface of the moving target to be measured is a rough surface, the signal detection module comprises a Gaussian filter device and a photodetector, the Gaussian filter device extracts the base mode in the signal light, the photodetector is placed behind the Gaussian filter device to receive the base mode echo Doppler signal, and the speed of the moving target is calculated by analyzing the Fourier spectrum. The linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is superimposed by two different radial wave vectors of Bessel light, and the speed of the moving target is calculated: Wherein, f0 is the base frequency of the two Bessel lights, v is the speed of the target to be measured along the optical axis, c is the speed of light, |Δf| is the detected Doppler frequency peak, α1 is the ratio of the radial wave vector of the first Bessel light to the global wave vector, and α2 is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

[0015] Compared with the prior art, the above technical scheme of the present application has the following beneficial effects:

[0016] 1. The application is based on the principle of structural Doppler effect, which is a novel physical mechanism of light-matter interaction, and is innovative compared to typical Doppler velocimetry methods, and is instructive for more general velocimetry research.

[0017] 2. The application provides a general direct detection scheme for Doppler measurement technology, and the Doppler signal itself contains beat frequency information related to velocity without reference light path, which is of great significance for the design and stability of the detection device in practical applications.

[0018] 3. The application uses different radial angle spectrum distribution superposition light field as structured light, i.e. single beam structured light irradiation, and then receives single beam echo signal, so that the measurement device is simple and more compact, and the integration degree is easy to improve and the cost is reduced, and the measurement result is less affected by environmental interference. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a conceptual schematic diagram of a structural Doppler velocimeter provided by the application;

[0020] Figure 2 is a device schematic diagram of a structural Doppler velocimeter provided by the embodiment of the application, wherein the object to be measured is a mirror surface;

[0021] Figure 3 is a device schematic diagram of a structural Doppler velocimeter provided by the embodiment of the application, wherein the object to be measured is a mirror surface and the probe light field is a superposition of two different radial wave vectors of high-order Bessel light;

[0022] Figure 4 is a device schematic diagram of a structural Doppler velocimeter provided by the embodiment of the application, wherein the object to be measured is a rough surface;

[0023] Figure 5 is a device schematic diagram of a structural Doppler velocimeter provided by the embodiment of the application, wherein the object to be measured is a rough surface; DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0025] The present application provides a kind of structural Doppler velocimeter, comprising: light source module, light field modulation module, signal detection module,

[0026] The light source module is used to emit Gaussian beam, the Gaussian beam generates specific structured light carrying transverse wave vector component after the light field modulation module, the structured light has phase lag effect, includes two different radial angular spectrum distribution;The structured light field is incident to the motion target to be measured, and the echo Doppler signal generated is received by the signal detection module, and the signal detection module is used to carry out data processing analysis to the received Doppler signal, and the motion speed of the motion target to be measured is calculated.

[0027] The structured light with transverse wave vector has phase lag effect, includes two different radial angular spectrum distribution, the propagation delay of light field is regulated by designing the radial angular spectrum distribution of structured light, the two different radial angular spectrum distribution can control the longitudinal propagation factor of light field, and Doppler beat frequency is caused.

[0028] Further preferably, the light field modulation module includes a polarizer, a half-wave plate, a first beam splitter, a spatial light modulator, a first lens, an aperture, a second lens, a second beam splitter, the Gaussian beam emitted by the light source module is adjusted to linearly polarized Gaussian light by the polarizer, the linearly polarized Gaussian light is adjusted in polarization direction by the half-wave plate, and is converted into linearly polarized Gaussian light corresponding to the optimal polarization direction of the spatial light modulator, the linearly polarized Gaussian light is modulated by the spatial light modulator after passing through the first beam splitter to obtain structured light, the structured light is reflected by the first beam splitter again, and the first diffraction order is filtered out by the 4-f optical system composed of the first lens, the aperture and the second lens, the filtered structured light is incident to the motion object to be measured through the second beam splitter, and the returned echo Doppler signal is reflected to the signal detection module by the second beam splitter.

[0029] Further preferably, the spatial light modulator can also be replaced by a digital micromirror array or a specially designed conical lens, so as to generate a structured light field with a specific radial wave vector, generate and superimpose different modes to synthesize a single-beam probe light field transmitted coaxially.

[0030] Further preferably, when the surface of the to-be-detected moving target is a mirror surface, the signal detection module comprises a light barrier and a photodetector, the light barrier is a slit placed at the center or a pinhole placed off-axis, the photodetector is placed behind the light barrier to locally receive the echo Doppler signal, and Fourier analysis is performed on the signal to extract the speed information of the moving target.

[0031] The linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is obtained by superimposing Bessel light and Gaussian light, and the calculated speed of the to-be-detected moving target is v = c|Δf| / α 2 f0. Wherein, f0 is the base frequency of the Bessel light and the Gaussian light, v is the speed of the to-be-detected target along the optical axis direction, c is the speed of light, |Δf| is the detected frequency peak value, and α is the ratio of the radial wave vector of the Bessel light to the global wave vector.

[0032] The linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is obtained by superimposing two Bessel lights with different radial wave vectors, and the speed of the moving target is calculated as follows: Wherein, f0 is the base frequency of the two Bessel lights, v is the speed of the to-be-detected target along the optical axis direction, c is the speed of light, |Δf| is the detected frequency peak value, α1 is the ratio of the radial wave vector of the first Bessel light to the global wave vector, and α2 is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

[0033] Further preferably, when the surface of the to-be-detected moving target is a mirror surface, the signal detection module is a camera, the camera is placed at the detection end to directly receive the echo Doppler signal, the rotational angular velocity of the signal light spot is observed by the camera, the speed of the moving target is inferred according to the size of the rotational angular velocity, and the direction of the speed of the moving target is inferred according to the direction of the rotational angular velocity.

[0034] The linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through the first beam splitter, the structured light is obtained by superimposing two high-order Bessel lights with different radial wave vectors, and the light spot can be observed to rotate at a constant speed on the signal light observation surface, and the speed of the moving target is calculated as follows: v = Ω·cΔl / 2πf0Δα 2 . Wherein, f0 is the base frequency of the two Bessel lights, v is the speed of the to-be-detected target along the optical axis direction, c is the speed of light, Ω is the rotation speed of the light spot, Δα = (α1-α2)2 is the square difference of the ratio of the radial wave vector of the two high-order Bessel lights to the global wave vector, and Δl = l1-l2 is the difference between the topological charges of the two high-order Bessel lights.

[0035] Further preferably, when the surface of the to-be-detected moving target is rough, the signal detection module comprises a Gaussian filter device and a photoelectric detector, the Gaussian filter device extracts the fundamental mode in the signal light, the photoelectric detector is arranged behind the Gaussian filter device to receive the fundamental mode echo Doppler signal, and the speed of the moving target is calculated by analyzing the Fourier spectrum. The linearly polarized Gaussian light is modulated by a spatial light modulator to obtain structured light after passing through a first beam splitter, the structured light is superimposed by two kinds of Bessel light with different radial wave vectors, and the speed of the moving target is calculated. Wherein, f0 is the fundamental frequency of the two kinds of Bessel light, v is the speed of the to-be-detected target along the optical axis direction, c is the speed of light, |Δf is the detected Doppler frequency peak value, α1 is the ratio of the radial wave vector of the first Bessel light to the global wave vector, and α2 is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

[0036] The following is described in combination with specific embodiments and the accompanying drawings.

[0037] As shown in the accompanying drawings, Figure 1 The present application provides a conceptual schematic diagram of a structured Doppler velocimeter, which comprises a laser light source, an optical field modulation module and a signal detection module. The laser light source emits Gaussian light, and the optical field modulation module generates a specific structured light field carrying a transverse wave vector component as a detection light field. The structured light with a transverse wave vector has a phase lag effect and contains two different radial angular spectrum distributions. The structured detection light field irradiates a to-be-detected moving target, and the generated echo Doppler signal is received by the signal detection module. According to different kinds of detection light fields, the detection module has a corresponding composition form. Finally, the signal is processed and analyzed to further calculate the speed of the target, thereby realizing the function of structured Doppler velocity measurement.

[0038] As shown in the accompanying drawings, Figure 2As shown in the figure, the schematic diagram of the structured Doppler velocimeter with a mirror-like surface as the test object provided in the embodiment of the present invention includes: a laser 1, an adjustable attenuator 2, a beam expander 3, a polarizer 4, a half-wave plate 5, a first beam splitter 6, a spatial light modulator 7, a first lens 8, an aperture 9, a second lens 10, a second beam splitter 11, a moving object to be tested 12, an aperture 13, and a first photodetector 14. Laser 1 outputs a Gaussian beam. The output power of the Gaussian beam is controlled by an adjustable attenuator 2, and then expanded by a beam expander 3. The expanded Gaussian beam is polarized linearly by a polarizer 4. The linearly polarized Gaussian beam is then polarized by a half-wave plate 5 to align with the optimal polarization direction of the spatial light modulator. After passing through a first beam splitter 6, the Gaussian beam is modulated by a spatial light modulator 7 to obtain a structured light field with a specific radial angular spectrum distribution. The structured light field is then reflected by the first beam splitter 6 and filtered out by a 4-f optical system consisting of a first lens 8, an aperture 9, and a second lens 10 to form a high-quality structured light field as the probe light field. The probe light field is directly irradiated onto the moving object 12 under test by a second beam splitter 11. The returned Doppler signal is then reflected by the second beam splitter 11 to the detection end. The detection end includes an aperture 13 and a first photodetector 14. The Doppler frequency shift is analyzed from the signal received by the first photodetector 14 to calculate the velocity of the moving target under test.

[0039] like Figure 3 As shown in the figure, the structural Doppler velocimeter provided in this embodiment of the invention is a device for a high-order Bessel light superposition case where the object to be measured is a mirror and the detection light field is a superposition of two different radial wave vectors. It includes: a laser 1, an adjustable attenuator 2, a beam expander 3, a polarizer 4, a half-wave plate 5, a first beam splitter 6, a spatial light modulator 7, a first lens 8, an aperture 9, a second lens 10, a second beam splitter 11, a moving object to be measured 12, and a camera 15. Laser 1 outputs a Gaussian beam. The output power of the Gaussian beam is controlled by an adjustable attenuator 2, and then expanded by a beam expander 3. The expanded Gaussian beam is polarized linearly by a polarizer 4. The linearly polarized Gaussian beam is then polarized by a half-wave plate 5 to align with the optimal polarization direction of the spatial light modulator. After passing through a first beam splitter 6, the Gaussian beam is modulated by a spatial light modulator 7 to obtain a structured light field with a specific radial angular spectrum distribution. The structured light field is then reflected by the first beam splitter 6 and filtered out by a 4-f optical system consisting of a first lens 8, an aperture 9, and a second lens 10 to form a high-quality structured light field as the probe light field. The probe light field is directly irradiated onto the moving object 12 under test by a second beam splitter 11. The returned echo Doppler signal is then reflected by the second beam splitter 11 to the detection end. The detection end is a camera 15. The speed of the moving target under test is calculated by analyzing the rotational speed of the rotating signal spot received by the camera 15 to determine the Doppler frequency shift.

[0040] like Figure 4As shown in the figure, the schematic diagram of the structured Doppler velocimeter device provided in the embodiment of the present invention for a rough surface object includes: a laser 1, an adjustable attenuator 2, a beam expander 3, a polarizer 4, a half-wave plate 5, a first beam splitter 6, a spatial light modulator 7, a first lens 8, an aperture 9, a second lens 10, a second beam splitter 11, a moving object to be measured 12, a single-mode fiber coupling device 16, and a second photodetector 17. Laser 1 outputs a Gaussian beam. The output power of the Gaussian beam is controlled by an adjustable attenuator 2, and then expanded by a beam expander 3. The expanded Gaussian beam is polarized linearly by a polarizer 4. The linearly polarized Gaussian beam is then polarized by a half-wave plate 5 to align with the optimal polarization direction of the spatial light modulator. After passing through a first beam splitter 6, the Gaussian beam is modulated by a spatial light modulator 7 to obtain a structured light field with a specific radial angular spectrum distribution. The structured light field is then reflected by the first beam splitter 6 and filtered out by a 4-f optical system consisting of a first lens 8, an aperture 9, and a second lens 10 to form a high-quality structured light field as the probe light field. The probe light field is directly irradiated onto the moving object 12 under test by a second beam splitter 11. The returned Doppler signal is then reflected by the second beam splitter 11 to the detection end. The detection end includes a single-mode fiber coupler 16 and a second photodetector 17. The Doppler frequency shift is analyzed by the fundamental mode signal received by the second photodetector 17 to calculate the velocity of the moving target under test.

[0041] like Figure 5 As shown in the figure, the signal diagrams of the superimposed light field of Bessel and Gaussian beams provided in this embodiment of the invention are shown under different pyramidal α. The Bessel beam carries the topological charge. The value is 2, and the speed is 5 cm / s. (a) is the time-domain signal of the superimposed light field of Bessel and Gaussian light with α = 0.0025 at a typical speed. (b) is the Fourier spectrum signal obtained from the superimposed light field of Bessel and Gaussian light with α = 0.0025. (c) is the time-domain signal obtained from the superimposed light field of Bessel and Gaussian light with α = 0.0035355. (d) is the Fourier spectrum signal obtained from the superimposed light field of Bessel and Gaussian light with α = 0.0035355. (e) is a cropped image of the light spot rotation obtained from the camera of the superimposed light field of Bessel and Gaussian light with α = 0.0025. It can be seen from the time-domain and frequency-domain signal diagrams that the locally received Doppler signal is independent of whether the probe light carries orbital angular momentum, and is only related to the difference in radial angular spectral components and the speed of the moving target. The screenshot in (e) showing the rotation of the light spot over time demonstrates that the rotation speed of the light spot detected by the camera is related to the speed of the moving target. Moreover, when the speed of the moving target is reversed, the rotation direction of the light spot will also be reversed.

[0042] The present application is not limited to the above-mentioned specific embodiments, and those skilled in the art can implement the present application by using other various embodiments according to the content disclosed in the present application. Therefore, any design that uses the design structure and idea of the present application and makes some simple changes or modifications falls within the scope of the present application.

Claims

1. A structural Doppler velocimeter, characterized in that, Includes a light source module, a light field modulation module, and a signal detection module. The light source module emits a Gaussian beam, which is then passed through the light field modulation module to generate a specific structured light carrying a transverse wave vector component. This structured light exhibits a phase lag effect and contains two distinct radial angular spectrum distributions. The phase lag effect is achieved by designing the radial angular spectrum distribution of the structured light to modulate the propagation delay of the light field. The two distinct radial angular spectrum distributions control the longitudinal propagation factor of the light field, inducing a Doppler beat frequency. When the structured light field is incident on the moving target, the resulting echo Doppler signal is received by the signal detection module. This module processes and analyzes the received Doppler signal to calculate the velocity of the moving target. The optical field modulation module includes a polarizer, a half-wave plate, a first beam splitter, a spatial light modulator, a first lens, an aperture stop, a second lens, and a second beam splitter. The Gaussian beam emitted by the light source module is adjusted into linearly polarized Gaussian light by the polarizer. The linearly polarized Gaussian light is then adjusted in polarization direction by the half-wave plate to convert it into linearly polarized Gaussian light corresponding to the optimal polarization direction of the spatial light modulator. The linearly polarized Gaussian light is then modulated by the spatial light modulator to obtain structured light after passing through the first beam splitter. The structured light is then reflected by the first beam splitter and filtered out by the first diffraction order through a 4-f optical system composed of the first lens, the aperture stop, and the second lens. The filtered structured light is then incident on the moving object under test through the second beam splitter. The returned echo Doppler signal is then reflected by the second beam splitter to the signal detection module.

2. The structural Doppler velocimeter according to claim 1, characterized in that, When the surface of the moving target to be measured is a mirror, the signal detection module includes an aperture and a photodetector. The aperture is a centrally placed slit or an off-axis aperture. The photodetector is placed after the aperture to receive the echo Doppler signal and perform Fourier analysis on the signal to extract the velocity information of the moving target.

3. The structural Doppler velocimeter according to claim 2, characterized in that, The structured light generated by the optical field modulation module is composed of the superposition of Bessel and Gaussian light, and the velocity of the moving target under test is calculated as follows: in, f 0 is the fundamental frequency of Bessel and Gaussian light. v Let be the velocity of the target along the optical axis. c At the speed of light, To detect the peak value of the Doppler frequency, This is the ratio of the radial wave vector of the Bessel light to the global wave vector.

4. The structural Doppler velocimeter according to claim 2, characterized in that, The structured light generated by the optical field modulation module is composed of the superposition of two Bessel beams with different radial wave vectors, used to calculate the velocity of the moving target. in, f 0 represents the fundamental frequency of both types of Bessel light. v Let be the velocity of the target along the optical axis. c At the speed of light, To detect the peak value of the Doppler frequency, This is the ratio of the radial wave vector of the first Bessel light to the global wave vector. This is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

5. The structural Doppler velocimeter according to claim 1, characterized in that, When the surface of the moving target to be measured is a mirror, the signal detection module includes a camera, which is used to receive echo Doppler signals, infer the speed of the moving target based on the magnitude of the rotational angular velocity of the light spot, and infer the speed direction of the moving target based on the direction of the rotational angular velocity.

6. The structural Doppler velocimeter according to claim 5, characterized in that, The structured light generated by the optical field modulation module is composed of the superposition of two high-order Bessel beams with different radial wave vectors, used to calculate the velocity of a moving target. in, f 0 represents the fundamental frequency of both types of Bessel light. v Let be the velocity of the target along the optical axis. c At the speed of light, For the rotation speed of the light spot, Let be the squared difference of the ratios of the radial wave vectors to the global wave vectors of the two higher-order Bessel lights. The difference in orbital angular momentum topological charge between two higher-order Bessel lights is represented by the difference in orbital angular momentum.

7. The structural Doppler velocimeter according to claim 1, characterized in that, When the surface of the moving target to be measured is rough, the signal detection module includes a Gaussian filter and a photodetector. The Gaussian filter is used to extract the fundamental mode from the echo Doppler signal, and the photodetector is placed after the Gaussian filter to receive the fundamental mode and analyze the Fourier spectrum to calculate the velocity of the moving target.

8. The structural Doppler velocimeter according to claim 7, characterized in that, The structured light generated by the optical field modulation module is composed of the superposition of two Bessel beams with different radial wave vectors, used to calculate the velocity of the moving target. in, f 0 represents the fundamental frequency of both types of Bessel light. v Let be the velocity of the target along the optical axis. c At the speed of light, To detect the peak value of the Doppler frequency, This is the ratio of the radial wave vector of the first Bessel light to the global wave vector. This is the ratio of the radial wave vector of the second Bessel light to the global wave vector.

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