Remote speed measurement method and system based on partially coherent rotation Doppler effect

Abstract

The invention belongs to the technical field of rotational motion, and relates to a remote speed measurement method and system based on a partially coherent rotational Doppler Effect. Gaussian-Schell model partially coherent light is modulated into a circular polarization state and then is irradiated to a rotating object to be measured, and elliptically polarized light reflected by the rotating object to be measured is modulated by using a rotating linear polarizer; generating a first periodic time-domain light beam related to polarization information, screening the first periodic time-domain light beam by using a post-modulation mask of a three-hole structure to obtain a second periodic time-domain light beam related to rotation speed information, and performing Fourier transform on the second periodic time-domain light beam to obtain a Fourier spectrum; acquiring a polarization peak signal and a rotation peak signal in the Fourier spectrum, calculating the angular velocity of the rotating object to be measured based on the frequency of the rotation peak signal, and obtaining the polarization response of the rotating object to be measured based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal. According to the scheme, the rotating speed of an off-axis object can be accurately measured, and polarization response characteristics are obtained.

Description

Technical Field

[0001] This invention relates to the field of rotational motion technology, and in particular to a remote velocity measurement method and system based on the partially coherent rotating Doppler effect. Background Technology

[0002] The Doppler effect quantitatively reveals the relationship between frequency shifts caused by relative motion and velocity. With its outstanding advantages such as non-contact operation, fast response, wide bandwidth, high spatial resolution, and long-range measurement, this effect has found wide application in fields such as astronomical observation, atomic cooling, precision metrology, and laser remote sensing. However, the traditional linear Doppler effect can only detect the radial translational velocity of a target and cannot directly obtain the object's rotational angular velocity. This limitation spurred the research on the rotating Doppler effect, which, by analyzing the frequency shift after the interaction between an orbital angular momentum beam and a rotating object, enables the direct measurement of the object's rotational velocity.

[0003] Currently, the main methods for measuring rotational speed using the rotating Doppler effect are as follows: 1. Detection by constructing a structured light field with superimposed positive and negative topological charges. This involves generating two spiral phase beams with opposite signs on a spatial light modulator, modulating the beams into a single ring with a radial intensity structure of p=0 Laguerre-Gaussian mode and a petal structure with twice the topological charge in the angular direction. The modulated structured light is then irradiated onto the rough surface of an object, and the rotational speed is measured by the beat frequency signal of the scattered light. 2. Signal propagation using multi-core optical fiber. A seven-core optical fiber is used for signal transmission, with the outer six cores serving as the transmission channels for the probe light. Selective excitation generates a specific spatial intensity distribution. After scattering by the rotating object, the middle core collects the scattered light signal, which is then transmitted back to the signal receiver via the optical fiber. The time-domain signal is then analyzed using Fourier transform. 3. Velocity measurement is achieved by using an incoherent structured light source as illumination. A petal-shaped intensity pattern is formed using an incoherent light projector and incident on the rotating target. The time-domain signal of the total light intensity is received by a photodetector, and the object's rotational speed is obtained by performing a Fourier transform on the time-domain signal. 4. At the transmitting end, a fundamental mode Gaussian beam is used to illuminate the rotating object, and the amplitude and spiral phase of the Gaussian beam are modulated by the rotating object to form a scattered light field. At the receiving end, a vortex beam is used as a reference light. The fundamental mode component in the scattered light of the reference light beats with the various orbital angular momentum modes in the received echo signal light of the rotating object. The different modes in the echo signal light are mapped onto the rotating Doppler spectrum to achieve multimode reception of the echo signal light. Finally, the vortex beam is used as a reference light, and the beat frequency is used for measurement. However, in the above measurement methods, the rotation axis of the rotating object and the center of the light source must be precisely aligned. Otherwise, the distance or angle from different scattering points on the rotating object to the detector will change differently with rotation, resulting in the superposition of multiple signals of different frequencies in the time-domain light intensity signal. This causes multiple frequency components to appear in the spectrum after Fourier transform, i.e., frequency broadening, which in turn causes the characteristic frequency corresponding to the rotation speed to be submerged, making it impossible to accurately obtain the rotation speed of the rotating object. At the same time, the above methods can only measure the rotation speed of the object and cannot obtain the polarization information of the rotating object, resulting in a single measurement dimension.

[0004] In summary, existing methods for measuring rotational speed based on the rotational Doppler effect have the problems of failing to accurately obtain the rotational speed of the rotating object when it rotates off-axis, failing to obtain the polarization information of the rotating object, and having a single measurement dimension. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of existing rotational speed measurement methods based on the rotational Doppler effect, which cannot accurately obtain the rotational speed of the rotating object when the object rotates off-axis, and cannot obtain the polarization information of the rotating object, and have a single measurement dimension.

[0006] To address the aforementioned technical problems, this invention provides a remote velocity measurement method based on the partially coherent rotating Doppler effect, comprising: The laser beam is modulated to generate Gaussian-Sherman mode partially coherent light, and the Gaussian-Sherman mode partially coherent light is modulated into a circularly polarized state; The modulated Gaussian-Sherman mode partially coherent light is irradiated onto the rotating object under test, and the elliptically polarized light reflected from the rotating object under test is obtained. Elliptically polarized light is modulated using a rotating linear polarizer to generate a first periodic time-domain beam related to polarization information; the first periodic time-domain beam is filtered using a three-hole post-modulation mask to obtain a second periodic time-domain beam related to rotational speed information. The Fourier spectrum is obtained by performing a Fourier transform on the second-period time-domain beam, and two peak signals in the Fourier spectrum are obtained. The peak signal whose horizontal coordinate is equal to twice the rotational speed of the linear polarizer is taken as the polarization peak signal, and the remaining peak signal is taken as the rotational peak signal. The angular velocity of the rotating object under test is calculated based on the frequency of the rotation peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal.

[0007] Preferably, the angular velocity of the rotating object under test is calculated based on the frequency of the rotation peak signal, including: Substituting the cross-spectral density of the Gaussian-Sherman mode partially coherent light, the transmittance function of the rotating object under test, and the pulse function of the post-modulation mask of the three-hole structure into the cross-spectral density formula of the second periodic time-domain beam, the light intensity distribution of the second periodic time-domain beam on the receiving plane is obtained. The angular period of the light intensity distribution in the receiving plane is obtained by using an enumeration method based on the light intensity distribution of the second periodic time-domain beam in the receiving plane; The angular velocity of the rotating object under test is obtained by multiplying the angular period of the light intensity distribution with the frequency of the rotation peak signal.

[0008] Preferably, the cross-spectral density of the Gaussian-Sherlock partially coherent light is expressed as: , in, This represents the cross-spectral density of partially coherent light in the Gaussian-Sherlock mode; , Represents the vector coordinates in the spatial domain of any two points in a Gaussian-Sherlock mode partially coherent beam; It is a constant; This represents the beam waist width of the Gaussian-Sherlock partial coherent light; It represents the coherence length of the Gaussian-Sherlock partial coherent light; The transmittance function of the rotating object under test is expressed as: , in, The transmittance function represents the transmissivity of the rotating object being measured. ; Represents the Dirac function; This represents the position vector of the first hole on the rotating object being measured; This represents the position vector of the second hole on the rotating object being measured; This represents the position vector of the third hole on the rotating object being measured; The pulse function of the post-modulation mask with a three-hole structure is expressed as: , in, The pulse function representing the post-modulation mask of the three-hole structure; This represents the radius of each hole on the post-modulation mask of the three-hole structure; Indicates the wavelength of light incident on the post-modulation mask of the three-hole structure; Represents the equivalent focal length for far-field transmission; Represents the imaginary unit; Represents the first-order Bessel function; This represents the position vector of the first hole on the post-modulation mask of the three-hole structure; This represents the position vector of the second hole on the post-modulation mask of the three-hole structure; This represents the position vector of the third hole on the post-modulation mask of the three-hole structure; The cross spectral density of the second periodic time-domain beam is expressed as: , in, This represents the cross spectral density of the second periodic time-domain beam; , This represents the vector coordinates of any two points in the second periodic time-domain beam in the far-field plane of the spatial domain; Indicates conjugate.

[0009] Preferably, the intensity distribution of the second periodic time-domain beam on the receiving plane is expressed as: , in, This represents the intensity distribution of the second periodic time-domain beam on the receiving plane; ; , ; , .

[0010] Preferably, the angular period of the light intensity distribution in the receiving plane is ; angular velocity of the rotating object to be measured The calculation formula is: , in, This indicates the frequency of the rotating peak signal.

[0011] Preferably, the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal, including: After modulating the Gaussian-Sherman mode partially coherent light into a circularly polarized state, the Jones matrix of the Gaussian-Sherman mode partially coherent light in the modulated circularly polarized state is obtained. Based on the modulation characteristics of the polarization response of the rotating object under test to the electric field component in the Jones matrix when the object reflects the partially coherent light of the modulated Gaussian-Sher modulus, the intensity expression of the first periodic time-domain beam related to the polarization information is obtained. Based on the expression for the light intensity of the first periodic time-domain beam related to polarization information, it is found that the amplitude of the polarization peak signal is proportional to the difference between the light intensity of the electric field component perpendicular to the incident plane and the light intensity of the electric field component parallel to the incident plane in the Jones matrix. Based on the fact that the amplitude of the rotating peak signal is proportional to the intensity of the elliptically polarized light reflected by the rotating object under test, it is found that the amplitude of the rotating peak signal is proportional to the sum of the light intensities of the electric field components perpendicular to the incident plane and the electric field components parallel to the incident plane in the Jones matrix. The polarization response function of the rotating object under test is equal to the ratio of the difference and sum of the light intensity of the electric field components perpendicular to the incident plane and the electric field components parallel to the incident plane in the Jones matrix. The polarization response of the rotating object under test is equal to the ratio of the amplitude of the polarization peak signal to the amplitude of the rotation peak signal.

[0012] Preferably, the Jones matrix of the Gaussian-Sherlock partial coherent light in the modulated circularly polarized state is expressed as: , in, The Jones matrix representing the Gaussian-Sherlock partial coherent light in the modulated circularly polarized state; This represents the electric field component perpendicular to the incident plane; This represents the electric field component parallel to the incident plane; Represents the imaginary unit; The intensity expression for the first periodic time-domain beam related to polarization information is as follows: ， in, The intensity of the first periodic time-domain beam, which is related to polarization information; The intensity of light is represented by the electric field component perpendicular to the incident plane. The intensity of light is represented by the electric field component parallel to the incident plane. This represents the rotational angular velocity of the rotating linear polarizer that modulates elliptically polarized light.

[0013] Preferably, the polarization response function of the rotating object under test Represented as: .

[0014] This invention also provides a remote velocity measurement system based on the partially coherent rotating Doppler effect, used to implement the aforementioned remote velocity measurement method based on the partially coherent rotating Doppler effect, comprising: A laser is used to generate a laser beam. A beam expander is used to expand a laser beam. The first modulation module is used to modulate the expanded laser beam to generate Gaussian-Sherlock mode partially coherent light; The second modulation module is used to modulate the Gaussian-Sherlock partial coherent light into a circularly polarized state and illuminate the rotating object under test. A rotating linear polarizer is used to modulate the elliptically polarized light reflected from a rotating object under test, generating a first periodic time-domain beam related to the polarization information. A three-hole post-modulation mask is used to filter the first periodic time-domain beam to obtain a second periodic time-domain beam related to the rotational speed information. The Fourier transform module is used to perform Fourier transform on the second-period time-domain beam; A photodetector is used to acquire the second-period time-domain beam after Fourier transform; The host computer, connected to the photodetector, is used to obtain the Fourier spectrum of the second-period time-domain beam after Fourier transform, and to acquire two peak signals in the Fourier spectrum. The peak signal whose horizontal coordinate is equal to twice the rotational speed of the rotating linear polarizer is taken as the polarization peak signal, and the remaining peak signal is taken as the rotational peak signal. The angular velocity of the rotating object under test is calculated based on the frequency of the rotational peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotational peak signal.

[0015] Preferably, the first modulation module includes a first lens, a frosted glass, and a second lens arranged sequentially along the optical path propagation direction; the second modulation module includes a linear polarizer and a quarter-glass plate arranged sequentially along the optical path propagation direction; and the Fourier transform module includes a third lens, an aperture, a fourth lens, and a fifth lens arranged sequentially along the optical path propagation direction.

[0016] The remote velocity measurement method based on the partially coherent rotating Doppler effect provided in this application has the following advantages: First, the laser source is modulated to generate Gaussian-Sherlock partially coherent light. Since this beam is less sensitive to phase differences at scattering points, modulating it into a circularly polarized state imparts rotational symmetry. When this light illuminates a rotating object under test, the light scattered from multiple scattering points on the object is incoherently superimposed, preventing frequency superposition and thus avoiding frequency broadening that could hinder accurate acquisition of rotational speed-related frequencies. Furthermore, the elliptically polarized light reflected from the rotating object contains both the periodic signal of the object's rotation and the cluttered signal from off-axis scattering points. Modulating this light with a rotating linear polarizer converts the periodic signal of the object's rotation into a polarization-modulated periodic signal, filtering out the cluttered signal from the scattering points. This results in a first periodic time-domain beam containing... The method incorporates the polarization information of the object and then uses a three-hole post-modulation mask to filter it. This ensures that the temporal periodic variation of the second periodic time-domain beam is determined only by the rotational angular velocity of the rotating object under test, and is independent of the position of a single scattering point and the off-axis distance. Finally, the Fourier spectrum obtained by performing a Fourier transform on the second periodic time-domain beam contains only polarization-related peak signals and rotational speed-related peak signals. Thus, the rotational speed and polarization response of the rotating object under test can be obtained simultaneously based on the two peak signals. This application utilizes a partially coherent beam and modulates it to not only achieve accurate rotational speed measurement of off-axis objects, but also simultaneously acquire the polarization information of the object. There is no need to add an additional polarization detection step, and the dual extraction of rotational speed and polarization can be completed in one go. Attached Figure Description

[0017] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 A flowchart illustrating a remote velocity measurement method based on the partially coherent rotating Doppler effect provided in an embodiment of this application; Figure 2 A schematic diagram of the structure of a remote velocity measurement system based on the partially coherent rotating Doppler effect provided in an embodiment of this application; Figure 3 To simultaneously measure the Fourier spectrum of an object's polarization response and rotational speed using the system provided in this application; wherein, Figure 3 (a) in the figure is the Fourier spectrum when the incident angle of the beam is 3° and the material of the rotating object to be measured is strontium titanate. Figure 3 (b) is the Fourier spectrum when the incident angle of the beam is 3° and the material of the rotating object being measured is zinc oxide. Figure 3 (c) in the figure is the Fourier spectrum when the incident angle of the beam is 3° and the material of the rotating object under test is alumina. Figure 3 In the figure, (d) is the Fourier spectrum when the incident angle of the beam is 15° and the material of the rotating object being measured is strontium titanate. Figure 3 In the diagram, (e) is the Fourier spectrum when the incident angle of the light beam is 15° and the material of the rotating object being measured is zinc oxide. Figure 3 In the diagram, (f) is the Fourier spectrum when the incident angle of the beam is 15° and the material of the rotating object being measured is alumina. Figure 3 In the figure, (g) is the Fourier spectrum when the incident angle of the light beam is 30° and the material of the rotating object to be measured is strontium titanate. Figure 3 In the figure, (h) is the Fourier spectrum when the incident angle of the light beam is 30° and the material of the rotating object being measured is zinc oxide. Figure 3 In the figure, (i) is the Fourier spectrum when the incident angle of the beam is 30° and the material of the rotating object to be measured is alumina; Figure 4 This application provides a system for measuring the Fourier spectrum of a rotating object at different off-axis distances using the system provided in this application; wherein, Figure 4 (a) in the figure is the Fourier spectrum of the rotating object when it is 2 mm off-axis. Figure 4 (b) in the figure is the Fourier spectrum of the rotating object when it is 4 mm off-axis. Figure 4 (c) in the figure is the Fourier spectrum of the rotating object when it is 6 mm off-axis. Figure 4 (d) in the figure is the Fourier spectrum of the rotating object when it is 8 mm off the axis; Explanation of reference numerals in the accompanying drawings: 1. Laser; 2. Beam expander; 3. First modulation module; 31. First lens; 32. Frosted glass; 33. Second lens; 4. Second modulation module; 41. Linear polarizer; 42. Quarter glass plate; 5. Rotating linear polarizer; 6. Post-modulation module with three-hole structure; 7. Fourier transform module; 71. Third lens; 72. Aperture; 73. Fourth lens; 74. Fifth lens; 8. Photodetector; 9. Host computer; 10. Rotating object under test. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0019] Please see Figure 1 , Figure 1 The diagram shows a flowchart of a remote velocities measurement method based on the partially coherent rotating Doppler effect provided in this application. The method specifically includes steps S10-S50: S10: Modulate the laser beam to generate Gaussian-Sherman mode partially coherent light, and modulate the Gaussian-Sherman mode partially coherent light into a circularly polarized state.

[0020] S20: Illuminate the rotating object under test with the modulated Gaussian-Sherman mode partially coherent light to obtain the elliptically polarized light reflected by the rotating object under test.

[0021] S30: Modulate elliptically polarized light using a rotating linear polarizer to generate a first periodic time-domain beam related to polarization information; use a three-hole post-modulation mask to filter the first periodic time-domain beam to obtain a second periodic time-domain beam related to rotational speed information.

[0022] S40: Perform a Fourier transform on the second-period time-domain beam to obtain the Fourier spectrum, and acquire two peak signals in the Fourier spectrum; take the peak signal whose horizontal coordinate is equal to twice the rotational speed of the linear polarizer as the polarization peak signal, and take the remaining peak signal as the rotational peak signal.

[0023] S50: The angular velocity of the rotating object under test is calculated based on the frequency of the rotation peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal.

[0024] Specifically, the angular velocity of the rotating object under test is calculated based on the frequency of the rotation peak signal in step S50, including steps 1-1 to 1-3: Step 1-1: Substitute the cross-spectral density of the Gaussian-Sher modal coherent light, the transmittance function of the rotating object under test, and the pulse function of the post-modulation mask of the three-hole structure into the cross-spectral density formula of the second periodic time-domain beam to obtain the light intensity distribution of the second periodic time-domain beam on the receiving plane.

[0025] Specifically, the cross-spectral density of the Gaussian-Sherlock partial coherent light is expressed as: , in, This represents the cross-spectral density of partially coherent light in the Gaussian-Sherlock mode; , Represents the vector coordinates in the spatial domain of any two points in a Gaussian-Sherlock mode partially coherent beam; It is a constant; This represents the beam waist width of the Gaussian-Sherlock partial coherent light; It represents the coherence length of the Gaussian-Sher modal partially coherent light.

[0026] The transmittance function of the rotating object under test is expressed as: , in, The transmittance function represents the transmissivity of the rotating object being measured. ; Represents the Dirac function; This represents the position vector of the first hole on the rotating object being measured; This represents the position vector of the second hole on the rotating object being measured; This represents the position vector of the third hole on the rotating object being measured.

[0027] The pulse function of the post-modulation mask with a three-hole structure is expressed as: , in, The pulse function representing the post-modulation mask of the three-hole structure; This represents the radius of each hole on the post-modulation mask of the three-hole structure; Indicates the wavelength of light incident on the post-modulation mask of the three-hole structure; Represents the equivalent focal length for far-field transmission; Represents the imaginary unit; Represents the first-order Bessel function; This represents the position vector of the first hole on the post-modulation mask of the three-hole structure; This represents the position vector of the second hole on the post-modulation mask of the three-hole structure; This represents the position vector of the third hole on the post-modulation mask of the three-hole structure.

[0028] Specifically, after the Gauss-Sher modal partially coherent light is reflected by the rotating object under test and then propagates in the far field, its correlation is distributed in a hexagonal lattice. After being filtered by a three-hole post-modulation mask, a periodic time-domain signal related to the rotational speed can be generated.

[0029] Specifically, the cross spectral density of the second periodic time-domain beam is expressed as: , in, This represents the cross spectral density of the second periodic time-domain beam; , This represents the vector coordinates of any two points in the second periodic time-domain beam in the far-field plane of the spatial domain; Indicates conjugate.

[0030] Furthermore, the intensity distribution of the second periodic time-domain beam on the receiving plane is expressed as: , in, This represents the intensity distribution of the second periodic time-domain beam on the receiving plane; ; , ; , .

[0031] Step 1-2: Using the enumeration method, obtain the angular period of the light intensity distribution in the receiving plane based on the light intensity distribution of the second periodic time-domain beam in the receiving plane.

[0032] Specifically, based on the light intensity distribution of the second periodic time-domain beam on the receiving plane... , , , The value of , Total The terms can be proven, through enumeration, to exhibit the following light intensity distribution in the receiving plane: The cycle.

[0033] Steps 1-3: Based on the product of the angular period of the light intensity distribution and the frequency of the rotation peak signal, the angular velocity of the rotating object under test is obtained.

[0034] Specifically, due to the distribution of light intensity in the receiving plane exhibiting The period represents the rotation of the rotating object under test. The light intensity will repeat once, meaning that the change in light intensity on the receiving plane will produce a specific frequency (i.e., the frequency corresponding to the first peak in the Fourier spectrum). Therefore, the angular velocity of the rotating object being measured... The calculation formula is: , in, This indicates the frequency of the rotating peak signal.

[0035] Furthermore, if we consider an off-axis rotating object, in the formula for the intensity distribution of the second periodic time-domain beam on the receiving plane, we use... replace , replace ,in Representing the off-axis distance of the rotating object, after replacing the parameters, the formula for the intensity distribution of the second periodic time-domain beam on the receiving plane shows that... remain unchanged. Become , Become ,at this time, It can be viewed as a whole and represented as This is equivalent to shifting the position vectors in the entire receiving plane by a certain distance. Since the beam intensity distribution of each position vector in the receiving plane exhibits... The period of light intensity, i.e., the overall translation of the position, does not change the periodic pattern of light intensity. Therefore, the periodic frequency of light intensity change (the frequency of the rotating peak signal) does not change, and the off-axis distance of the object does not affect the angular velocity measurement results.

[0036] Further, in step S50, the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal, including steps 2-1 to 2-5: Step 2-1: After modulating the Gaussian-Sherman mode partially coherent light into a circularly polarized state, obtain the Jones matrix of the Gaussian-Sherman mode partially coherent light in the modulated circularly polarized state.

[0037] Specifically, the Jones matrix of the partially coherent Gaussian-Sherlock mode light in the modulated circularly polarized state is expressed as: , in, The Jones matrix representing the Gaussian-Sherlock partial coherent light in the modulated circularly polarized state; This represents the electric field component perpendicular to the incident plane; This represents the electric field component parallel to the incident plane; It represents the imaginary unit.

[0038] Step 2-2: Based on the modulation characteristics of the polarization response of the rotating object under test to the electric field component in the Jones matrix when the object reflects the modulated Gaussian-Sherman mode partially coherent light, obtain the light intensity expression of the first periodic time-domain beam related to the polarization information.

[0039] Specifically, the intensity expression of the first periodic temporal beam related to polarization information is as follows: ， in, The intensity of the first periodic time-domain beam, which is related to polarization information; The intensity of light is represented by the electric field component perpendicular to the incident plane. The intensity of light is represented by the electric field component parallel to the incident plane. This represents the rotational angular velocity of the rotating linear polarizer that modulates elliptically polarized light.

[0040] Steps 2-3: Based on the intensity expression of the first periodic time-domain beam related to polarization information, the amplitude of the polarization peak signal is proportional to the difference between the intensity of the electric field component perpendicular to the incident plane and the intensity of the electric field component parallel to the incident plane in the Jones matrix.

[0041] Steps 2-4: Based on the fact that the amplitude of the rotating peak signal is proportional to the intensity of the elliptically polarized light reflected by the rotating object under test, it is found that the amplitude of the rotating peak signal is proportional to the sum of the intensity of the electric field component perpendicular to the incident plane and the intensity of the electric field component parallel to the incident plane in the Jones matrix.

[0042] Steps 2-5: Based on the polarization response function of the rotating object under test, which is equal to the ratio of the difference and sum of the light intensity of the electric field component perpendicular to the incident plane and the electric field component parallel to the incident plane in the Jones matrix, the polarization response of the rotating object under test is obtained, which is equal to the ratio of the amplitude of the polarization peak signal to the amplitude of the rotation peak signal.

[0043] Specifically, the polarization response function of the rotating object under test is expressed as: .

[0044] It can be seen that, With polarization ellipticity It shows a negative correlation.

[0045] Specifically, the actual detected Fourier spectrum shows two peaks, one representing the polarization signal and the other representing the rotational speed signal, since the rotational speed of the rotating linear polarizer is... The abscissa of the polarization signal is locked at This can be distinguished from the rotational speed signal; the rotational speed of the rotating object under test can be calculated using the above rotational speed formula and the abscissa of the rotational peak signal, and then the polarization response can be obtained by taking the ratio of the ordinates of the two peak signals.

[0046] This application also provides a remote velocity measurement system based on the partially coherent rotating Doppler effect, such as... Figure 2 As shown, the system specifically includes a laser 1, a beam expander 2, a first modulation module 3, a second modulation module 4, a rotating linear polarizer 5, a three-hole post-modulation module 6, a Fourier transform module 7, a photodetector 8, and a host computer 9.

[0047] Laser 1 is used to generate a laser beam.

[0048] Beam expander 2 is used to expand the laser beam.

[0049] The first modulation module 3 is used to modulate the expanded laser beam to generate Gaussian-Sherlock mode partially coherent light.

[0050] The second modulation module 4 is used to modulate the Gaussian-Sherman mode partially coherent light into a circularly polarized state and illuminate the rotating object 10 to be tested.

[0051] The rotating linear polarizer 5 is used to modulate the elliptically polarized light reflected from the rotating object 10 under test, generating a first periodic time-domain beam related to the polarization information.

[0052] The three-hole post-modulation mask 6 is used to filter the first periodic time-domain beam to obtain a second periodic time-domain beam related to the rotational speed information.

[0053] The Fourier transform module 7 is used to perform Fourier transform on the second-period time-domain beam.

[0054] Photodetector 8 is used to acquire the second periodic time-domain beam after Fourier transform.

[0055] The host computer 9 is connected to the photodetector 8 to obtain the Fourier spectrum based on the second-period time-domain beam after Fourier transform, and to acquire two peak signals in the Fourier spectrum; the peak signal whose horizontal coordinate is equal to twice the rotational speed of the rotating linear polarizer is taken as the polarization peak signal, and the remaining peak signal is taken as the rotational peak signal; the angular velocity of the rotating object under test is calculated based on the frequency of the rotational peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotational peak signal.

[0056] Furthermore, the first modulation module 3 includes a first lens 31, a frosted glass 32, and a second lens 33 arranged sequentially along the optical path propagation direction; the second modulation module 4 includes a linear polarizer 41 and a quarter-glass plate 42 arranged sequentially along the optical path propagation direction; and the Fourier transform module 7 includes a third lens 71, an aperture 72, a fourth lens 73, and a fifth lens 74 arranged sequentially along the optical path propagation direction.

[0057] Specifically, the expanded laser source generates Gaussian-Sherlock partial coherent light through a modulation module with rotating frosted glass on the focal plane. This light is then modulated into a circularly polarized state by the modulation module. After reflection from a rotating object with a polarization response, the reflected light becomes elliptically polarized. This elliptically polarized light is then modulated to generate a polarization-related periodic time-domain signal. Simultaneously, due to the three-hole structure of the rotating object, its correlation distribution after far-field transmission is a hexagonal lattice distribution. After being filtered by a post-modulation mask with a three-hole structure, a periodic time-domain signal related to the rotational speed is generated. Two peaks can be observed in the Fourier spectrum obtained after performing a Fourier transform on the periodic time-domain signal: one for the polarization signal and the other for the rotational speed signal. The rotational speed of the rotating object is calculated by reading the abscissa of the rotational speed signal peak, and the polarization response of the rotating object is obtained by the ratio of the ordinates of the two signal peaks.

[0058] The following two specific embodiments further explain the above-mentioned remote velocity measurement method and system based on the partially coherent rotating Doppler effect: Embodiment 1 of this application utilizes the aforementioned remote velocity measurement system based on the partially coherent rotating Doppler effect to simultaneously measure the polarization response and rotational speed of an object, such as... Figure 3 The image shown is a schematic diagram of the test results, in which... Figure 3 In (a), the incident angle of the light beam is 3° and the material of the rotating object being measured is strontium titanate (SrTiO2). Fourier spectrum at time Figure 3 In (b), the incident angle of the light beam is 3° and the material of the rotating object being measured is zinc oxide (ZrO2). Fourier spectrum at time Figure 3 In the diagram, (c) represents a beam incident angle of 3° and the material of the rotating object being measured is alumina. Fourier spectrum at time Figure 3 In the figure, (d) represents a beam incident angle of 15° and the material of the rotating object being measured is strontium titanate (SrTiO2). Fourier spectrum at time Figure 3 In the figure, (e) indicates that the incident angle of the light beam is 15° and the material of the rotating object being measured is zinc oxide (ZrO2). Fourier spectrum at time Figure 3 In the figure, (f) represents a beam incident angle of 15° and the material of the rotating object being measured is aluminum oxide. Fourier spectrum at time Figure 3 In the figure, (g) represents a beam incident angle of 30° and the material of the rotating object being measured is strontium titanate (SrTiO2). Fourier spectrum at time Figure 3 In this context, (h) represents a beam incident angle of 30° and the material of the rotating object being measured is zinc oxide (ZrO2). Fourier spectrum at time Figure 3 In the diagram, (i) represents a beam incident angle of 30° and the material of the rotating object being measured is aluminum oxide. Fourier spectrum of time.

[0059] Since the rotational speed of the linear polarizer is 0.1 Hz, the abscissa of the polarization peak signal is fixed at 0.2 Hz, and the abscissa of the rotational peak signal is 3 Hz. Therefore, the rotational speed of the object under test can be calculated to be 0.5 Hz. The polarization response of the object under test can then be obtained based on the ratio of the amplitudes of the two peak signals. For example, Figure 3 In (a), (d), and (g), when the material of the rotating object to be tested is strontium titanate (SrTiO2). When the incident angles are 3°, 15°, and 30°, the ellipticity of the reflected light increases with the increase of the angle, and the peak value of the polarization signal at 0.2 Hz will increase. However, the peak value of the rotational speed signal at 3 Hz will decrease due to the decrease in the total intensity of reflected light. Therefore, the spectrum provides two independent observable values: the abscissa of the 3 Hz main peak provides information on the object's rotational speed, and the ratio of the 0.2 Hz peak value to the 3 Hz peak value yields the object's polarization response. Furthermore, if the incident angle of the beam is fixed, changing only the material of the rotating object reveals that a lower refractive index produces a higher polarization response. However, judging the polarization response solely based on the 0.2 Hz peak value may be erroneous because the 0.2 Hz peak value is also proportional to the total intensity of reflected light. For example, at a 30° incident angle, zinc oxide shows a higher 0.2 Hz peak value than aluminum oxide. However, due to the reduced reflectivity at a lower refractive index, the 3 Hz main peak value is lower. Therefore, it is necessary to determine the polarization response of the rotating object by obtaining the ratio of the amplitudes of the two peaks.

[0060] Embodiment 2 of this application utilizes the aforementioned remote velocimetry system based on the partially coherent rotating Doppler effect to simultaneously measure the rotational speed of an off-axis rotating object, such as... Figure 4 The figure shows the Fourier spectrum of a rotating object at different off-axis distances, where, Figure 4 (a) in the figure is the Fourier spectrum of the rotating object when it is 2 mm off-axis. Figure 4 (b) in the figure is the Fourier spectrum of the rotating object when it is 4 mm off-axis. Figure 4 (c) in the figure is the Fourier spectrum of the rotating object when it is 6 mm off-axis. Figure 4 (d) is the Fourier spectrum of the rotating object when it is 8 mm off the axis.

[0061] from Figure 4 As can be seen, when the off-axis distance of the rotating object is 6mm, the rotational speed of the rotating object can still be calculated using the abscissa of the main peak. Since the object in this embodiment consists of three small holes with a diameter of 1mm and a spacing of 2mm between adjacent holes, this off-axis distance is almost three times the size of the object, thus greatly reducing the requirements for optical path collimation in outdoor experiments. It should also be noted that the incident angle during the measurement process is 3°, and the rotating object is a strontium titanate reflective object.

[0062] The laser used in Examples 1 and 2 above is a Ventus laser with a wavelength of 532nm and a power of 1.5W. The photodetector is a PDA100A2 with a diameter of 75.4mm. 2 The photodetector transmits the collected signal to the acquisition card, which is an NI USB-6366. The acquisition card then transmits the signal to the host computer, where MATLAB software records and saves the time-domain signal of the light intensity and performs subsequent calculations.

[0063] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0064] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0065] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0066] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0067] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A remote velocity measurement method based on the partially coherent rotating Doppler effect, characterized in that, include: The laser beam is modulated to generate Gaussian-Sherman mode partially coherent light, and the Gaussian-Sherman mode partially coherent light is modulated into a circularly polarized state; The modulated Gaussian-Sherman mode partially coherent light is irradiated onto the rotating object under test, and the elliptically polarized light reflected from the rotating object under test is obtained. Elliptically polarized light is modulated using a rotating linear polarizer to generate a first periodic time-domain beam related to polarization information; the first periodic time-domain beam is filtered using a three-hole post-modulation mask to obtain a second periodic time-domain beam related to rotational speed information. The Fourier spectrum is obtained by performing a Fourier transform on the second-period time-domain beam, and two peak signals in the Fourier spectrum are obtained. The peak signal whose horizontal coordinate is equal to twice the rotational speed of the linear polarizer is taken as the polarization peak signal, and the remaining peak signal is taken as the rotational peak signal. The angular velocity of the rotating object under test is calculated based on the frequency of the rotation peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotation peak signal.

2. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 1, characterized in that, The angular velocity of the rotating object under test is calculated based on the frequency of the rotating peak signal, including: Substituting the cross-spectral density of the Gaussian-Sherman mode partially coherent light, the transmittance function of the rotating object under test, and the pulse function of the post-modulation mask of the three-hole structure into the cross-spectral density formula of the second periodic time-domain beam, the light intensity distribution of the second periodic time-domain beam on the receiving plane is obtained. The angular period of the light intensity distribution in the receiving plane is obtained by using an enumeration method based on the light intensity distribution of the second periodic time-domain beam in the receiving plane; The angular velocity of the rotating object under test is obtained by multiplying the angular period of the light intensity distribution with the frequency of the rotation peak signal.

3. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 2, characterized in that, The cross-spectral density of partially coherent Gaussian-Sherlock mode light is expressed as: ， in, This represents the cross-spectral density of partially coherent light in the Gaussian-Sherlock mode; , Represents the vector coordinates in the spatial domain of any two points in a Gaussian-Sherlock mode partially coherent beam; It is a constant; This represents the beam waist width of the Gaussian-Sherlock partial coherent light; It represents the coherence length of the Gaussian-Sherlock partial coherent light; The transmittance function of the rotating object under test is expressed as: ， in, The transmittance function represents the transmissivity of the rotating object being measured. ; Represents the Dirac function; This represents the position vector of the first hole on the rotating object being measured; This represents the position vector of the second hole on the rotating object being measured; This represents the position vector of the third hole on the rotating object being measured; The pulse function of the post-modulation mask with a three-hole structure is expressed as: ， in, The pulse function representing the post-modulation mask of the three-hole structure; This represents the radius of each hole on the post-modulation mask of the three-hole structure; Indicates the wavelength of light incident on the post-modulation mask of the three-hole structure; Represents the equivalent focal length for far-field transmission; Represents the imaginary unit; Represents the first-order Bessel function; This represents the position vector of the first hole on the post-modulation mask of the three-hole structure; This represents the position vector of the second hole on the post-modulation mask of the three-hole structure; This represents the position vector of the third hole on the post-modulation mask of the three-hole structure; The cross spectral density of the second periodic time-domain beam is expressed as: ， in, This represents the cross spectral density of the second periodic time-domain beam; , This represents the vector coordinates of any two points in the second periodic time-domain beam in the far-field plane of the spatial domain; Indicates conjugate.

4. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 3, characterized in that, The intensity distribution of the second periodic time-domain beam on the receiving plane is represented as follows: ， in, This represents the intensity distribution of the second periodic time-domain beam on the receiving plane; ; , ; , .

5. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 2, characterized in that, The angular period of the light intensity distribution in the receiving plane is ; angular velocity of the rotating object to be measured The calculation formula is: ， in, This indicates the frequency of the rotating peak signal.

6. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 1, characterized in that, Based on the amplitudes of the polarization peak signal and the rotation peak signal, the polarization response of the rotating object under test is obtained, including: After modulating the Gaussian-Sherman mode partially coherent light into a circularly polarized state, the Jones matrix of the Gaussian-Sherman mode partially coherent light in the modulated circularly polarized state is obtained. Based on the modulation characteristics of the polarization response of the rotating object under test to the electric field component in the Jones matrix when the object reflects the partially coherent light of the modulated Gaussian-Sher modulus, the intensity expression of the first periodic time-domain beam related to the polarization information is obtained. Based on the expression for the light intensity of the first periodic time-domain beam related to polarization information, it is found that the amplitude of the polarization peak signal is proportional to the difference between the light intensity of the electric field component perpendicular to the incident plane and the light intensity of the electric field component parallel to the incident plane in the Jones matrix. Based on the fact that the amplitude of the rotating peak signal is proportional to the intensity of the elliptically polarized light reflected by the rotating object under test, it is found that the amplitude of the rotating peak signal is proportional to the sum of the light intensities of the electric field components perpendicular to the incident plane and the electric field components parallel to the incident plane in the Jones matrix. Based on the polarization response function of the rotating object under test, which is equal to the ratio of the difference and sum of the light intensity of the electric field component perpendicular to the incident plane and the electric field component parallel to the incident plane in the Jones matrix, we can obtain that the polarization response of the rotating object under test is equal to the ratio of the amplitude of the polarization peak signal to the amplitude of the rotation peak signal.

7. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 6, characterized in that, The Jones matrix of the partially coherent Gaussian-Sherlock mode light in the modulated circularly polarized state is expressed as: ， in, The Jones matrix representing the Gaussian-Sherlock partial coherent light in the modulated circularly polarized state; This represents the electric field component perpendicular to the incident plane; This represents the electric field component parallel to the incident plane; Represents the imaginary unit; The intensity expression for the first periodic time-domain beam related to polarization information is as follows: ， in, The intensity of the first periodic time-domain beam, which is related to polarization information; The intensity of light is represented by the electric field component perpendicular to the incident plane. The intensity of light is represented by the electric field component parallel to the incident plane. This represents the rotational angular velocity of the rotating linear polarizer that modulates elliptically polarized light.

8. The remote velocity measurement method based on the partially coherent rotating Doppler effect according to claim 7, characterized in that, Polarization response function of the rotating object under test Represented as: 。 9. A remote velocity measurement system based on the partially coherent rotating Doppler effect, characterized in that, The method for implementing the remote velocity measurement method based on the partially coherent rotating Doppler effect as described in any one of claims 1 to 8 includes: A laser is used to generate a laser beam. A beam expander is used to expand a laser beam. The first modulation module is used to modulate the expanded laser beam to generate Gaussian-Sherlock mode partially coherent light; The second modulation module is used to modulate the Gaussian-Sherlock partial coherent light into a circularly polarized state and illuminate the rotating object under test. A rotating linear polarizer is used to modulate the elliptically polarized light reflected from a rotating object under test, generating a first periodic time-domain beam related to the polarization information. A three-hole post-modulation mask is used to filter the first periodic time-domain beam to obtain a second periodic time-domain beam related to the rotational speed information. The Fourier transform module is used to perform Fourier transform on the second-period time-domain beam; A photodetector is used to acquire the second-period time-domain beam after Fourier transform; The host computer, connected to the photodetector, is used to obtain the Fourier spectrum of the second-period time-domain beam after Fourier transform, and to acquire two peak signals in the Fourier spectrum. The peak signal whose horizontal coordinate is equal to twice the rotational speed of the rotating linear polarizer is taken as the polarization peak signal, and the remaining peak signal is taken as the rotational peak signal. The angular velocity of the rotating object under test is calculated based on the frequency of the rotational peak signal, and the polarization response of the rotating object under test is obtained based on the amplitude of the polarization peak signal and the amplitude of the rotational peak signal.

10. The remote velocity measurement system based on the partially coherent rotating Doppler effect according to claim 9, characterized in that, The first modulation module includes a first lens, a frosted glass, and a second lens, which are arranged separately along the optical path propagation direction; the second modulation module includes a linear polarizer and a quarter-glass plate, which are arranged separately along the optical path propagation direction; the Fourier transform module includes a third lens, an aperture, a fourth lens, and a fifth lens, which are arranged separately along the optical path propagation direction.

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