CN-121978366-A - Remote speed measurement method and system based on partial coherence rotation Doppler effect

CN121978366ACN 121978366 ACN121978366 ACN 121978366ACN-121978366-A

Abstract

The invention belongs to the technical field of rotary motion, and relates to a remote speed measurement method and a remote speed measurement system based on a partial coherence rotary Doppler effect, which are characterized in that Gaussian-Xie Ermo partial coherence light is modulated into a circular polarization state and then irradiated to a rotary object to be measured, elliptical polarized light reflected by the rotary object to be measured is modulated by a rotary linear polarizer to generate a first periodic time domain beam related to polarization information, the first periodic time domain beam is screened by a post-modulation mask with a three-hole structure to obtain a second periodic time domain beam related to rotation speed information, fourier transformation is performed on the second periodic time domain beam to obtain a Fourier spectrum, a polarized peak signal and a rotary peak signal in the Fourier spectrum are obtained, the angular speed of the rotary object to be measured is obtained based on the frequency calculation of the rotary peak signal, and the polarization response of the rotary object to be measured is obtained based on the amplitude of the polarized peak signal and the amplitude of the rotary peak signal. The scheme can accurately measure the rotating speed of the off-axis object and acquire the polarization response characteristic.

Inventors

ZHAO CHENGLIANG
Hang Yiyi
LU XINGYUAN

Assignees

苏州大学

Dates

Publication Date: 20260505
Application Date: 20251230

Claims (10)

1. A remote speed measurement method based on a partial coherence rotational doppler effect, comprising: Modulating the laser beam to generate Gaussian-Xie Ermo partial coherent light, and modulating the Gaussian-Xie Ermo partial coherent light into a circular polarization state; Irradiating modulated Gaussian-Xie Ermo part of coherent light to a rotating object to be detected to obtain elliptical polarized light reflected by the rotating object to be detected; modulating the elliptical polarized light by using a rotating linear polarizer to generate a first periodic time domain light beam related to polarization information; screening the first periodic time domain light beam by using a rear modulation mask with a three-hole structure to obtain a second periodic time domain light beam related to the rotating speed information; Carrying out Fourier transform on the second periodic time domain light beam to obtain a Fourier spectrum, and obtaining two peak signals in the Fourier spectrum, wherein the peak signal with the abscissa equal to two times of the rotating speed of the rotating linear polaroid in the two peak signals is used as a polarized peak signal, and the residual peak signal is used as a rotating peak signal; and calculating the angular speed of the rotating object to be detected based on the frequency of the rotating peak signal, and obtaining the polarization response of the rotating object to be detected based on the amplitude of the polarization peak signal and the amplitude of the rotating peak signal.
2. The method for remote velocity measurement based on partial coherent rotational doppler effect according to claim 1, wherein the calculating of the angular velocity of the rotating object to be measured based on the frequency of the rotation peak signal comprises: Substituting the cross spectral density of Gaussian-Xie Ermo partially coherent light, the transmittance function of a rotating object to be detected and the pulse function of a rear modulation mask of a three-hole structure into a cross spectral density formula of a second periodic time domain light beam to obtain the light intensity distribution of the second periodic time domain light beam on a receiving plane; Acquiring the angle period of the light intensity distribution in the receiving plane based on the light intensity distribution of the second periodic time domain light beam in the receiving plane by using an enumeration method; And obtaining the angular velocity of the rotating object to be detected based on the product of the angular period of the light intensity distribution and the frequency of the rotating peak value signal.
3. The method for remote velocity measurement based on partially coherent rotational doppler effect according to claim 2, wherein the cross spectral density of gaussian-Xie Ermo partially coherent light is expressed as: , Wherein, the Represents the cross spectral density of the Gaussian-Xie Ermo partially coherent light; 、 The vector coordinates of any two points in the Gaussian-Xie Ermo partial coherent light beam in the space domain are shown; Is a constant; Represents the beam waist width of the Gaussian-Xie Ermo partially coherent light; Representing the coherence length of the Gaussian-Xie Ermo partial coherent light; the transmittance function of the rotating object to be measured is expressed as: , Wherein, the Representing the transmittance function of the rotating object to be measured, ; Representing a dirac function; a position vector representing a first hole in the rotating object to be measured; a position vector representing a second hole in the rotating object to be measured; a position vector representing a third hole in the rotating object to be measured; the pulse function of the post-modulation mask for the three-hole structure is expressed as: , Wherein, the A pulse function representing a post-modulation mask of a three-hole structure; Representing the radius of each hole on the post-modulation mask of the three-hole structure; Representing the wavelength of light incident on the post-modulation mask of the triple-hole structure; Representing the equivalent focal length of the far field transmission process; Representing imaginary units; Representing a first order Bessel function; a position vector representing a first aperture on the post-modulation mask of the three-aperture structure; a position vector representing a second aperture on the post-modulation mask of the three-aperture structure; a position vector representing a third aperture on the post-modulation mask of the three-aperture structure; the cross spectral density of the second periodic time domain beam is expressed as: , Wherein, the Representing the cross spectral density of the second periodic time domain beam; 、 representing vector coordinates of any two points in the second periodic time domain beam in a far-field plane of the space domain; representing conjugation.
4. A method of remote velocimetry based on the partially coherent rotational doppler effect according to claim 3, characterized in that the light intensity distribution of the second periodic time domain light beam in the receiving plane is expressed as: , Wherein, the Representing the light intensity distribution of the second periodic time domain light beam in the receiving plane; ; , ; , 。
5. The method for remote velocity measurement based on partial coherence rotational doppler effect according to claim 2, wherein 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 of (2) is as follows: , Wherein, the Representing the frequency of the rotated peak signal.
6. The method for remote velocity measurement based on partial coherence rotational doppler effect according to claim 1, wherein 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 comprises: after modulating Gaussian-Xie Ermo partial coherent light into a circular polarization state, acquiring a Jones matrix of modulated Gaussian-Xie Ermo partial coherent light in the circular polarization state; Acquiring a light intensity expression of a first periodic time domain light beam related to polarization information based on the modulation characteristic of the polarization response of the rotating object to be detected on the electric field component in the Jones matrix when the rotating object to be detected reflects the modulated Gaussian-Xie Ermo partial coherent light; Based on the light intensity expression of the first periodic time domain light beam related to the polarization information, the amplitude of the polarization peak signal is obtained in direct proportion to the difference value between the light intensity of the electric field component perpendicular to the incident surface and the light intensity of the electric field component parallel to the incident surface in the Jones matrix; based on the fact that the amplitude of the rotation peak signal is in direct proportion to the light intensity of elliptical polarized light reflected by the rotating object to be detected, the amplitude of the rotation peak signal is obtained in direct proportion to the sum of the light intensity of an electric field component perpendicular to the incident surface and the light intensity of an electric field component parallel to the incident surface in the Jones matrix; And obtaining the ratio of the polarization response of the rotating object to be measured to be equal to the amplitude of the polarization peak signal to the amplitude of the rotation peak signal based on the polarization response function of the rotating object to be measured, which is equal to the ratio of the sum value to the difference value of the light intensity of the electric field component perpendicular to the incident surface and the light intensity of the electric field component parallel to the incident surface in the Jones matrix.
7. The method for remote velocity measurement based on partial coherent rotational doppler effect according to claim 6, wherein the jones matrix of gaussian-Xie Ermo partial coherent light in modulated circular polarization state is expressed as: , Wherein, the A jones matrix representing modulated circular polarization gaussian-Xie Ermo partially coherent light; representing the electric field component normal to the plane of incidence; Representing the electric field component parallel to the plane of incidence; Representing imaginary units; The light intensity expression of the first periodic time domain light beam related to the polarization information is: , Wherein, the Representing the intensity of the first periodic time domain beam relative to the polarization information; Representing the intensity of the electric field component normal to the plane of incidence; representing the intensity of the electric field component parallel to the plane of incidence; The rotation angular velocity of the rotating linear polarizer modulating elliptically polarized light is shown.
8. The method for remote velocity measurement based on partial coherence rotational doppler effect according to claim 7, wherein the polarization response function of the rotating object to be measured Expressed as: 。
9. a remote speed measurement system based on the partial coherence rotational doppler effect, for implementing the remote speed measurement method based on the partial coherence rotational doppler effect according to any one of claims 1 to 8, comprising: A laser for generating a laser beam; the beam expander is used for expanding the laser beam; the first modulation module is used for modulating the laser beam after beam expansion to generate Gaussian-Xie Ermo partial coherent light; The second modulation module is used for modulating Gaussian-Xie Ermo partial coherent light into a circular polarization state and irradiating the circular polarization state to a rotating object to be detected; the rotating linear polaroid is used for modulating elliptical polarized light reflected by the rotating object to be detected and generating a first periodic time domain light beam related to polarization information; The post-modulation mask with the three-hole structure is used for screening the first periodic time domain light beam to obtain a second periodic time domain light beam related to the rotating speed information; the Fourier transform module is used for carrying out Fourier transform on the second periodic time domain light beam; The photoelectric detector is used for acquiring a second periodic time domain beam after Fourier transform; The upper computer is connected with the photoelectric detector and is used for obtaining a Fourier spectrum based on a second periodic time domain beam after Fourier transformation and obtaining two peak signals in the Fourier spectrum, taking the peak signal with the abscissa equal to twice of the rotating speed of the rotating linear polaroid in the two peak signals as a polarized peak signal and the residual peak signal as a rotating peak signal, calculating the angular velocity of the rotating object to be detected based on the frequency of the rotating peak signal, and obtaining the polarization response of the rotating object to be detected based on the amplitude of the polarized peak signal and the amplitude of the rotating peak signal.
10. The remote velocimetry system based on the partially coherent rotational doppler effect of claim 9, wherein the first modulation module comprises a first lens, a frosted glass and a second lens disposed separately in sequence along the direction of propagation of the optical path, the second modulation module comprises a linear polarizer and a quarter glass disposed separately in sequence along the direction of propagation of the optical path, and the fourier transform module comprises a third lens, a stop, a fourth lens and a fifth lens disposed separately in sequence along the method of propagation of the optical path.

Description

Remote speed measurement method and system based on partial coherence rotation Doppler effect Technical Field The invention relates to the technical field of rotary motion, in particular to a remote speed measurement method and system based on a partial coherent rotary Doppler effect. Background The Doppler effect quantitatively reveals the corresponding relation between the frequency offset and the speed caused by the relative motion, and the Doppler effect is widely applied to the fields of astronomical observation, atomic cooling, precise metering, laser remote sensing and the like by virtue of the outstanding advantages of non-contact, quick response, wide frequency band, high spatial resolution, remote measurement and the like. However, the traditional linear Doppler effect can only detect the translational velocity of a target along the radial direction, and can not directly acquire the rotation angular velocity of an object, so that the limitation has prompted the research of the rotation Doppler effect, and the direct measurement of the rotation velocity of the object is realized by analyzing the frequency shift after the interaction of the orbital angular momentum beam and the rotating object. The existing method for measuring the rotating speed by utilizing the rotating Doppler effect mainly comprises the following steps of 1, detecting by constructing a structural light field with superimposed positive and negative topological charges, modulating the light beam into a single ring with a radial strength structure of p=0 Laguerre-Gaussian mode by generating superposition of two spiral phase light beams with opposite signs on a spatial light modulator, illuminating the modulated structural light on the rough surface of an object, and measuring the rotating speed of the object by using beat frequency signals of scattered light; the method comprises the steps of 2, carrying out signal transmission by utilizing a multi-core optical fiber, carrying out signal transmission by utilizing a seven-core optical fiber, wherein six cores at the periphery are taken as transmission channels of detection light, generating specific spatial intensity distribution by selective excitation, scattering by a rotating object, collecting scattered light signals by a middle core, transmitting back to a signal receiving end by utilizing the optical fiber, carrying out Fourier transform on time domain signals to obtain object rotating speed, 3, carrying out speed measurement by utilizing an incoherent structure light source as illumination, forming petal-shaped intensity patterns by utilizing an incoherent light projector, incidence of the petal patterns on the rotating object, receiving time domain signals of total light intensity by utilizing a photoelectric detector, carrying out Fourier transform on the time domain signals to obtain object rotating speed, 4, irradiating a rotating object by utilizing a Gaussian beam with a fundamental mode at a transmitting end, carrying out amplitude and spiral phase modulation on the Gaussian beam by the rotating object to form a scattered light field, carrying out beat frequency on fundamental mode components in the scattered light of the reference light and each orbital angular momentum mode in the received rotating object echo signal light at a receiving end, mapping different modes in the echo signal light to rotating Doppler frequency spectrum, the multimode receiving of the echo signal light is realized, the vortex beam is finally used as reference light, and beat frequency is utilized for measurement. However, in the above-mentioned several measuring methods, the rotation axis of the rotating object and the center of the light source must be aligned precisely, otherwise, the distances or angles from different scattering points on the rotating object to the detector will be different along with the change rule of rotation, resulting in the superposition of time domain light intensity signals by a plurality of different frequency signals, so that a plurality of frequency components, i.e. frequency broadening, appear in the frequency spectrum after fourier transformation, and further result in the characteristic frequency corresponding to the rotation speed being submerged, and the rotation speed of the rotating object cannot be obtained accurately. In summary, the conventional rotational speed measurement method based on the rotational doppler effect has the problems that the rotational speed of the rotating object cannot be accurately obtained when the object rotates off-axis, the polarization information of the rotating object cannot be obtained, and the measurement dimension is single. Disclosure of Invention Therefore, the invention aims to solve the technical problems that the rotating speed measuring method based on the rotating Doppler effect in the prior art cannot accurately acquire the rotating speed of a rotating object when the object rotates off-axis, cannot acquire th