A method and system for detecting radial velocity in a flow field

Abstract

The application provides a method and system for detecting radial velocity of a flow field, and the system for detecting radial velocity of a flow field is used to generate a common Gaussian light beam and a high-order vortex light beam with a non-zero radial coefficient; the high-order vortex light beam is used to irradiate a measured fluid and pass through the measured fluid to generate target detection light carrying radial information of the fluid, and the common Gaussian light is interfered with the target detection light to generate a heterodyne interference signal; a detector is used to detect the heterodyne interference signal and analyze a Doppler spectrum; and the radial velocity of the measured fluid is determined according to the Doppler spectrum. When the detection light irradiates the measured fluid, fluid particles in the measured fluid move radially in a light spot of a high-order vortex light beam orthographic projection, the application uses the high-order vortex light with an intensity distribution in the radial direction to detect the flow field to generate a Doppler effect, so that the radial velocity of the flow field is detected, and therefore the application has a wide application scenario.

Description

Technical Field

[0001] This invention belongs to the field of target recognition and detection technology, specifically relating to a method and system for detecting radial velocity in a flow field. Background Technology

[0002] The ocean is rich in biological and mineral resources and hosts a large amount of human activity. Detecting ocean currents is beneficial for further utilizing marine resources and more effectively mitigating marine disasters. Various detection methods, from electromagnetic current meters to acoustic velocimeters and particle imaging technology, have long been applied to the detection of flow velocities.

[0003] Currently, commonly used methods for flow velocity detection mainly include the heat dissipation rate method, PIV technology, acoustic Doppler method, and optical Doppler velocimetry. The heat dissipation rate method places a heated flow velocity sensor in the fluid being measured. Utilizing the characteristic that the heat dissipation rate of the heated sensor is proportional to the fluid velocity, the flow velocity is obtained by measuring the sensor's heat dissipation rate. This method requires inserting a hot wire or hot film probe into the fluid being measured, which can cause significant interference to the flow field. PIV, short for Particle Image Velocimetry, uses a laser and other optical components to obtain a sheet light source, which illuminates the sheet containing tracer particles in the fluid being measured. A digital camera continuously photographs the illuminated area, obtaining a series of tracer particle positions at regular time intervals. Finally, image processing techniques are used to calculate the displacement of the same particles to obtain the flow velocity. PIV (Picture Indicator Vibration) technology requires the addition of tracer particles to the fluid being measured. Furthermore, because it necessitates continuous imaging and calculation of the measured area, it demands high equipment accuracy and sophisticated algorithms, resulting in relatively high costs. Acoustic and optical Doppler velocimetry both utilize the Doppler effect to detect flow velocity. Acoustic Doppler velocimetry is significantly affected by environmental noise and suffers from high transmission loss. Optical Doppler velocimetry calculates flow velocity along the beam propagation direction by analyzing the frequency shift of the echo spectrum; however, for radial velocity, multiple adjustments to the probe beam direction are required, limiting its application scenarios. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a method and system for detecting radial velocity in a flow field. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] This invention provides a method for detecting radial velocity in a flow field, comprising:

[0006] S100: A system for detecting the radial velocity of the flow field generates a regular Gaussian beam and a higher-order vortex beam with a non-zero radial coefficient.

[0007] S200: Uses ordinary Gaussian light as the reference light and a high-order vortex beam as the probe light;

[0008] S300: The probe light illuminates the fluid being measured and passes through the fluid to generate a target probe light carrying radial information of the fluid. The reference light and the target probe light are then interfered with to generate a heterodyne interference signal.

[0009] S400: Detects and analyzes heterodyne interference signals to obtain their Doppler spectrum;

[0010] S500: Determine the radial velocity of the fluid under test based on the Doppler spectrum of the heterodyne interference signal.

[0011] This invention provides a system for detecting radial velocity in a flow field, comprising:

[0012] The system includes a laser, a polarizer, a beam splitter 1, a detection path device, a reference path device, and an interference processing device. The laser, polarizer, and beam splitter 1 are connected in sequence. The beam splitter 1 is connected to the detection path device and the reference path device, respectively. The outputs of the detection path device and the reference path device are both connected to the interference processing device.

[0013] Laser, used to generate laser light;

[0014] A polarizer is used to receive laser light and generate polarized light that matches the polarization direction of a spatial light modulator.

[0015] Beam splitter 1 is used to split polarized light into a transmission beam and a reflection beam. The transmission beam is used as the incident light of the detection device, and the reflection beam is used as the incident light of the reference device.

[0016] The detection path device is used to generate a higher-order vortex beam under the action of the transmission path beam, filter out stray light from the higher-order vortex beam, and generate a target detection beam carrying radial information of the fluid through the fluid being measured.

[0017] The reference path device is used to generate a normal Gaussian beam under the action of the reflected beam, filter out stray light from the normal Gaussian beam, and change the transmission direction of the normal Gaussian beam so that it enters the interference processing device.

[0018] An interferometric processing device is used to generate a heterodyne interference signal by interfering a reference beam with a target probe beam, and to detect and analyze the heterodyne interference signal to determine the radial velocity of the fluid under test. This invention provides a method and system for detecting the radial velocity of a flow field. The system generates a regular Gaussian beam and a higher-order vortex beam with a non-zero radial coefficient. The higher-order vortex beam is used to illuminate the fluid under test and pass through it to generate a target probe beam carrying radial information of the fluid. The regular Gaussian beam is then interfered with the target probe beam to generate a heterodyne interference signal. A detector is used to detect and analyze the heterodyne interference signal to obtain the Doppler spectrum. The radial velocity of the fluid under test is determined based on the Doppler spectrum. Since fluid particles in the fluid under test undergo radial motion within the beam spot projected onto the higher-order vortex beam when the probe beam illuminates the fluid, this invention utilizes the higher-order vortex beam with intensity distribution in the radial direction to detect the flow field and generate the Doppler effect, thereby achieving the detection of the radial velocity of the flow field. Therefore, this invention has a wide range of applications.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the working principle of an acoustic Doppler velocimeter.

[0021] Figure 2 This is a schematic diagram of the principle of laser Doppler velocimetry in dual-beam-dual-scattering mode.

[0022] Figure 3 This is a schematic flowchart of a method for detecting radial velocity in a flow field provided by the present invention;

[0023] Figure 4 The diagram shows the variation of light intensity with radius for a topological charge number l of 10 and radial exponents p of 2 and 4, respectively.

[0024] Figure 5 The light intensity distribution diagrams are for vortex light with a topological charge of 10 and radial coefficients p of 2 and 4.

[0025] Figure 6 This is a schematic diagram of the structure of a system for detecting radial velocity in a flow field according to an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the Doppler frequency shift of the echo signal generated by a high-order vortex beam with a topological charge number l=10 and a radial coefficient p=2 incident on a moving fluid, provided in an embodiment of the present invention.

[0027] Figure 8 This is a graph showing the radial Doppler frequency shift as a function of radial velocity obtained from the incident flow field of a high-order vortex beam with a topological charge number l = 10 and radial coefficients p = 2 and 4, respectively, provided in an embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0029] The Doppler effect is an effect that links the velocity of an object to changes in the frequency of a wave field. Current technology utilizes the Doppler effect to fabricate Doppler velocimeters, thereby enabling the measurement of flow field velocities. (Reference) Figure 1 As shown, Figure 1 This is a schematic diagram illustrating the working principle of an acoustic Doppler velocimeter. Figure 2 The diagram illustrates the principle of laser Doppler velocimetry using a dual-beam, dual-scattering mode. Compared to acoustic methods, laser coherent Doppler velocimetry offers higher measurement accuracy and a wider measurement range. The laser beam is split into two equal and parallel beams by a beam splitter, which are then converged at the measurement point by a focusing lens. The Doppler frequency shift is obtained by heterodyning the scattered light from these two incident beams in the same direction.

[0030] This invention utilizes the radial Doppler effect to detect the radial velocity of the flow field on the beam transmission cross section, providing a unique radial velocity identification method. The solution provided by this invention will be described in detail below.

[0031] refer to Figure 3 As shown, the present invention provides a method for detecting radial velocity in a flow field, comprising:

[0032] S100: A system for detecting the radial velocity of the flow field generates a regular Gaussian beam and a higher-order vortex beam with a non-zero radial coefficient.

[0033] S200: Uses ordinary Gaussian light as the reference light and a high-order vortex beam as the probe light;

[0034] S300: The probe light illuminates the fluid being measured and passes through the fluid to generate a target probe light carrying radial information of the fluid, and the reference light and the target probe light are interfered with to generate a heterodyne interference signal;

[0035] When the probe light illuminates the fluid being measured, the fluid particles in the fluid move radially within the spot of the orthogonal projection of the higher-order vortex beam, thereby generating a target probe light carrying radial information of the fluid.

[0036] S400: Detects and analyzes heterodyne interference signals to obtain their Doppler spectrum;

[0037] S500: Determine the radial velocity of the fluid under test based on the Doppler spectrum of the heterodyne interference signal.

[0038] A vortex beam is a ring-shaped beam with a helical phase. Higher-order vortex beams with non-zero radial coefficients exhibit intensity and phase distributions in the radial direction that are also related to the radial coefficient. In cylindrical coordinates, the complex amplitude expression for a higher-order radial vortex beam located at the source plane is:

[0039]

[0040] Where ω0 is the beam waist radius, l is the topological charge, which determines the angular variation of the beam phase; and p is the radial coefficient, which determines the radial variation of the beam intensity. For p-th order |l| with respect to the variable The Laguerre polynomial has p distinct positive roots. (m=1,2,3…p), so The beam has p radial nodes.

[0041] Figure 4 The diagram shows the variation of light intensity with radius for a topological charge number l of 10 and radial exponents p of 2 and 4. Figure 5 The image shows the intensity distribution of vortex light with a topological charge of 10 and radial coefficients p of 2 and 4. From... Figure 4 as well as Figure 5 It can be seen that the higher-order vortex light with radial exponent p has p+1 maxima, and the intensity first decreases and then increases between each pair of maxima. This stable radial distribution of the higher-order vortex light intensity can be used to detect the radial velocity of the flow field. Assume the distance between each pair of maxima in the higher-order vortex light intensity distribution is R. m Then the p-th order vortex light has p different spacings R1, R2...R P For each p different spacing, the scattered echoes generated by a fluid with radial velocity will produce p different frequency shifts. For each measurement, the minimum spacing is taken. The corresponding maximum frequency shift can be obtained as a frequency shift that is linearly related to the magnitude of the radial velocity. Therefore, the radial velocity of the flow field can be identified and detected through this frequency shift.

[0042] Based on the above principles, this invention first generates a high-order vortex light with a non-zero radial coefficient, which is then used as a probe light to illuminate a two-dimensional flow field. Particles in the flow field move along their respective radial directions within the plane of the beam. After the probe light scattered by the moving particles interferes with the Gaussian light used as a reference light, the interference signal is received by a photomultiplier tube. Then, a spectrum analyzer is used to perform a Fourier transform on the echo signal to obtain the Doppler spectrum of the echo signal. Finally, the radial velocity of the flow field is determined based on the obtained Doppler spectrum of the echo signal.

[0043] In one specific embodiment of the present invention, S300 includes:

[0044] S310 applies a frequency shift to the reference light;

[0045] S320 generates a target probe light that carries radial information about the fluid by illuminating the probe light through the fluid being measured.

[0046] S330 deflects the direction of the reference light so that its direction is consistent with the target probe light, and performs interference between the reference light and the target probe light to generate a heterodyne interference signal.

[0047] refer to Figure 6 In a specific embodiment of the present invention, the system for detecting the radial velocity of the flow field in S100 includes: a laser, a polarizer, a beam splitter 1, a detection path device, a reference path device, and an interference processing device; the laser, polarizer, and beam splitter 1 are connected in sequence, the beam splitter 1 is connected to the detection path device and the reference path device respectively, and the outputs of the detection path device and the reference path device are both connected to the interference processing device.

[0048] Laser, used to generate laser light;

[0049] A polarizer is used to receive laser light and generate polarized light that matches the polarization direction of a spatial light modulator.

[0050] Beam splitter 1 is used to split polarized light into a transmission beam and a reflection beam. The transmission beam is used as the incident light of the detection device, and the reflection beam is used as the incident light of the reference device.

[0051] The detection path device is used to generate a higher-order vortex beam under the action of the transmission path beam, filter out stray light from the higher-order vortex beam, and generate a target detection beam carrying radial information of the fluid through the fluid being measured.

[0052] The reference path device is used to generate a normal Gaussian beam under the action of the reflected beam, filter out stray light from the normal Gaussian beam, and change the transmission direction of the normal Gaussian beam so that it enters the interference processing device.

[0053] The interferometric processing device is used to generate heterodyne interference signals by interfering the reference light with the target probe light, and to detect and analyze the heterodyne interference signals to determine the radial velocity of the fluid being measured.

[0054] The computer center is used to control the spatial light modulator to generate controllable high-order vortex light.

[0055] refer to Figure 6 In one specific embodiment of the present invention, the path detection device includes:

[0056] Beam splitter prism 2 is used to receive probe light and emit the probe light to beam expander;

[0057] A beam expander is used to receive the probe light from the beam splitter prism 2 and expand the probe light to send it to the spatial modulator.

[0058] A spatial light modulator is used to modulate the beam emitted after the beam is expanded by the beam expander to generate controllable high-order vortex light, and then feed it back to the beam expander.

[0059] A beam expander is used to focus high-order vortex light into a high-order vortex beam and feed it back to the beam splitter prism 2.

[0060] Beam splitter prism 2 is used to reflect higher-order vortex beams into the lens;

[0061] The lens is used to focus the higher-order vortex beam reflected by the beam splitter prism 2;

[0062] The pinhole aperture 1 is used to filter out the other orders of the beam in the higher-order vortex beam, allowing only the higher-order vortex beam to pass through the aperture and be incident on the fluid being measured, and to generate a target detection light carrying radial information through the fluid being measured.

[0063] refer to Figure 6 In one specific embodiment of the present invention, the reference path device includes:

[0064] An acousto-optic modulator is used to add a frequency shift to the reference light reflected by beam splitter 1 to generate a common Gaussian beam.

[0065] This invention utilizes an acousto-optic modulator to add an 80MHz frequency shift to Gaussian light, preventing the radial Doppler frequency shift caused by velocity from being buried in low-frequency noise.

[0066] The pinhole aperture 2 is used to filter out the beams of other orders in the ordinary Gaussian beam, and only allows the reference light with additional frequency shift to pass through the aperture and be incident on the beam splitter prism 3.

[0067] The beam splitter prism 3 is used to change the transmission direction of the ordinary Gaussian beam by reflection, so that the ordinary Gaussian beam is incident into the interference processing device.

[0068] refer to Figure 6 In one specific embodiment of the present invention, the interference processing device includes:

[0069] The beam splitter prism 4 is used to change the reference light reflected by the beam splitter prism 3 so that the transmission direction of the reference light is consistent with that of the target detection light, and the reference light and the target detection light interfere to generate heterodyne interference light.

[0070] A photomultiplier tube is used to receive heterodyne interference light transmitted through beam splitter 4 and convert it into heterodyne interference light signal;

[0071] A spectrum analyzer is used to connect to a photomultiplier tube to perform spectrum analysis on the heterodyne interference signal transmitted by the photomultiplier tube to obtain the Doppler spectrum.

[0072] The spectrum analyzer performs a Fourier transform on the heterodyne interference signal to obtain the Doppler spectrum.

[0073] refer to Figure 6 The present invention provides a system for detecting radial velocity in a flow field, comprising:

[0074] The system includes a laser, a polarizer, a beam splitter 1, a detection path device, a reference path device, and an interference processing device. The laser, polarizer, and beam splitter 1 are connected in sequence. The beam splitter 1 is connected to the detection path device and the reference path device, respectively. The outputs of the detection path device and the reference path device are both connected to the interference processing device.

[0075] Laser, used to generate laser light;

[0076] A polarizer is used to receive laser light and generate polarized light that matches the polarization direction of a spatial light modulator.

[0077] Beam splitter 1 is used to split polarized light into a transmission beam and a reflection beam. The transmission beam is used as the incident light of the detection device, and the reflection beam is used as the incident light of the reference device.

[0078] The detection path device is used to generate a higher-order vortex beam under the action of the transmission path beam, filter out stray light from the higher-order vortex beam, and generate a target detection beam carrying radial information of the fluid through the fluid being measured.

[0079] The reference path device is used to generate a normal Gaussian beam under the action of the reflected beam, filter out stray light from the normal Gaussian beam, and change the transmission direction of the normal Gaussian beam so that it enters the interference processing device.

[0080] The interferometric processing device is used to generate heterodyne interference signals by interfering the reference light with the target probe light, and to detect and analyze the heterodyne interference signals to determine the radial velocity of the fluid being measured.

[0081] refer to Figure 7 This invention provides a schematic diagram of the Doppler frequency shift of the echo signal generated by a high-order vortex beam with a topological charge number l=10 and a radial coefficient p=2 incident on a moving fluid; from Figure 7 As can be seen, the spectrum of the higher-order vortex light corresponding to the radial coefficient p=2 has two peaks, and the value with the larger frequency shift is taken as the observation value. It can be seen that as the radial velocity of the flow field increases, the obtained Doppler frequency shift also increases.

[0082] refer to Figure 8 This invention provides a radial Doppler frequency shift versus radial velocity curve obtained from the incident flow field of a high-order vortex beam with a topological charge number l = 10 and radial coefficients p = 2 and 4, respectively. From... Figure 8As can be seen, for vortex light with different radial coefficients, the radial Doppler frequency shift increases linearly with the increase of the radial velocity of the flow field; and for flow fields with the same radial velocity, vortex light with a larger radial coefficient produces a larger Doppler frequency shift.

[0083] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0084] Although this application has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality.

[0085] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for detecting radial velocity in a flow field, characterized in that, include: S100: A normal Gaussian beam and a higher-order vortex beam with non-zero radial coefficient are generated using a system for detecting the radial velocity of the flow field; the higher-order vortex beam with non-zero radial coefficient has an intensity distribution in the radial direction that is related to the radial coefficient, so as to detect the radial velocity of the flow field. S200: Uses ordinary Gaussian light as the reference light and a high-order vortex beam as the probe light; S300: The probe light irradiates the fluid under test and passes through the fluid to generate a target probe light carrying radial information of the fluid. The reference light and the target probe light are interfered to generate a heterodyne interference signal. When the probe light irradiates the fluid under test, the fluid particles in the fluid under test move radially within the spot of the orthogonal projection of the higher-order vortex beam. The flow field is detected by the intensity distribution of the higher-order vortex beam with non-zero radial coefficient in the radial direction to generate a radial Doppler effect, thereby generating a target probe light carrying radial information of the fluid. S400: Detects and analyzes heterodyne interference signals to obtain their Doppler spectrum; S500: Determine the radial velocity of the fluid under test based on the Doppler spectrum of the heterodyne interference signal.

2. The method for detecting radial velocity in a flow field according to claim 1, characterized in that, The S300 includes: S310 applies a frequency shift to the reference light; S320 generates a target probe light that carries radial information about the fluid by illuminating the probe light through the fluid being measured. S330 deflects the direction of the reference light so that its direction is consistent with the target probe light, and performs interference between the reference light and the target probe light to generate a heterodyne interference signal.

3. The method for detecting radial velocity in a flow field according to claim 1, characterized in that, The system for detecting the radial velocity of the flow field in S100 includes: a laser, a polarizer, a beam splitter 1, a detection path device, a reference path device, and an interference processing device; the laser, polarizer, and beam splitter 1 are connected in sequence, and the beam splitter 1 is connected to the detection path device and the reference path device respectively, and the outputs of the detection path device and the reference path device are both connected to the interference processing device. Laser, used to generate laser light; A polarizer is used to receive laser light and generate polarized light that matches the polarization direction of a spatial light modulator. Beam splitter 1 is used to split polarized light into a transmission beam and a reflection beam. The transmission beam serves as the incident light of the detection device, and the reflection beam serves as the incident light of the reference device. The detection path device is used to generate a higher-order vortex beam under the action of the transmission path beam, filter out stray light from the higher-order vortex beam, and generate a target detection beam carrying radial information of the fluid through the fluid being measured. The reference path device is used to generate a normal Gaussian beam under the action of the reflected beam, filter out stray light from the normal Gaussian beam, and change the transmission direction of the normal Gaussian beam so that it enters the interference processing device. The interference processing device is used to generate heterodyne interference signals by interfering the reference light with the target detection light, and to detect and analyze the heterodyne interference signals to determine the radial velocity of the fluid being measured.

4. The method for detecting radial velocity in a flow field according to claim 3, characterized in that, The detection path device includes: Beam splitter prism 2 is used to receive probe light and emit the probe light to beam expander; A beam expander is used to receive the probe light from the beam splitter prism 2 and expand the probe light to send it to the spatial modulator. A spatial light modulator is used to modulate the beam emitted after the beam is expanded by the beam expander to generate controllable high-order vortex light, and then feed it back to the beam expander. A beam expander is used to focus high-order vortex light into a high-order vortex beam and feed it back to the beam splitter prism 2. Beam splitter prism 2 is used to reflect higher-order vortex beams into the lens; The lens is used to focus the higher-order vortex beam reflected by the beam splitter prism 2; The pinhole aperture 1 is used to filter out the other orders of the beam in the higher-order vortex beam, allowing only the higher-order vortex beam to pass through the aperture and be incident on the fluid being measured, and to generate a target detection light carrying radial information through the fluid being measured.

5. The method for detecting radial velocity in a flow field according to claim 4, characterized in that, The reference path device includes: An acousto-optic modulator is used to add a frequency shift to the reference light reflected by beam splitter 1 to generate a common Gaussian beam. The pinhole aperture 2 is used to filter out the beams of other orders in the ordinary Gaussian beam, and only allows the reference light with additional frequency shift to pass through the aperture and be incident on the beam splitter prism 3. The beam splitter prism 3 is used to change the transmission direction of the ordinary Gaussian beam by reflection, so that the ordinary Gaussian beam is incident into the interference processing device.

6. The method for detecting radial velocity in a flow field according to claim 5, characterized in that, The interference processing device includes: The beam splitter prism 4 is used to change the reference light reflected by the beam splitter prism 3 so that the transmission direction of the reference light is consistent with that of the target detection light, and the reference light and the target detection light interfere to generate heterodyne interference light. A photomultiplier tube is used to receive heterodyne interference light transmitted through beam splitter 4 and convert it into heterodyne interference light signal; A spectrum analyzer is used to connect to a photomultiplier tube to perform spectrum analysis on the heterodyne interference signal transmitted by the photomultiplier tube to obtain the Doppler spectrum.

7. The method for detecting radial velocity in a flow field according to claim 6, characterized in that, The spectrum analyzer performs a Fourier transform on the heterodyne interference signal to obtain the Doppler spectrum of the heterodyne interference signal.

8. The method for detecting radial velocity in a flow field according to claim 4, characterized in that, The system for detecting the radial velocity of the flow field in S100 also includes: The computer center is used to control the spatial light modulator to generate controllable high-order vortex light.

9. A system for detecting radial velocity in a flow field, characterized in that, The system includes: The system includes a laser, a polarizer, a beam splitter 1, a detection path device, a reference path device, and an interference processing device. The laser, polarizer, and beam splitter 1 are connected in sequence. The beam splitter 1 is connected to the detection path device and the reference path device, respectively. The outputs of the detection path device and the reference path device are both connected to the interference processing device. Laser, used to generate laser light; A polarizer is used to receive laser light and generate polarized light that matches the polarization direction of a spatial light modulator. Beam splitter 1 is used to split the polarized light into a transmission beam and a reflection beam, with the transmission beam serving as the incident light of the detection device and the reflection beam serving as the incident light of the reference device. The detection path device is used to generate a high-order vortex beam with a non-zero radial coefficient under the action of the transmission path beam, filter out stray light from the high-order vortex beam, and generate a target detection beam carrying radial information of the fluid through the fluid being measured; the high-order vortex beam with a non-zero radial coefficient has an intensity distribution in the radial direction that is related to the radial coefficient, so as to detect the radial velocity of the flow field. The reference path device is used to generate a normal Gaussian beam under the action of the reflected beam, filter out stray light from the normal Gaussian beam, and change the transmission direction of the normal Gaussian beam so that it enters the interference processing device. The interferometric processing device is used to generate heterodyne interference signals by interfering the reference light and the target probe light, and to detect and analyze the heterodyne interference signals to determine the radial velocity of the fluid under test. When the probe light irradiates the fluid under test, the fluid particles in the fluid under test move radially within the spot of the orthographic projection of the higher-order vortex beam. The flow field is detected by using the intensity distribution of the higher-order vortex beam with non-zero radial coefficient in the radial direction to generate a radial Doppler effect, thereby generating a target probe light carrying the radial information of the fluid.

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