An ultra-resolution angular velocity vector measurement device and method

Abstract

The application relates to a super-resolution angular velocity vector measuring device and method. The super-resolution angular velocity vector measuring device and method allow a rotation axis of a to-be-measured object to deviate from the center of a light source and exist external jitter, and solve the problem that the rotation axis of the to-be-measured object and the center of the light source need to be strictly aligned in the prior art. The rotation movement of the to-be-measured object is tracked through the coherent structure of the rotating light source, when the two rotate in the same direction, the light beam is red-shifted; when the two rotate in opposite directions, the light beam is blue-shifted, so that the size and direction of the angular velocity can be determined at the same time. Through beat frequency, the gear up or down of the frequency shift can be flexibly controlled, and the angular velocity measurement in the range from super-low speed to super-high speed can be realized.

Description

Technical Field

[0001] This invention relates to the field of angular velocity measurement technology, and in particular to a super-resolution angular velocity vector measurement device and method. Background Technology

[0002] Angular velocity measurement plays a crucial role in industrial manufacturing and defense technology, and is widely used in precision metrology, aerospace, and other fields. Therefore, research on angular velocity measurement methods is of paramount importance. Contact measurement is a traditional method for measuring angular velocity, including the use of mechanical and electromagnetic induction sensors. However, due to its lower accuracy and susceptibility to electromagnetic interference, it can no longer meet the ever-increasing measurement demands.

[0003] The laser Doppler effect, due to its advantages such as non-contact operation, rapid response, high precision, high sensitivity, high spatial resolution, and long-distance measurement capabilities, is widely used in precision metrology, atomic cooling, astronomical observation, and laser remote sensing. Initially, the linear Doppler effect was used to infer the linear velocity of moving objects in laser Doppler velocity measurement. In 1998, Courtial et al. proposed the rotating Doppler effect of lasers. In 2013, Martin et al. applied the rotating Doppler effect of lasers to detect the angular velocity of objects. In the past decade, this rotating Doppler velocimetry method has received considerable attention. Currently, there are a series of studies on laser rotating Doppler velocimetry using various scenarios and detection methods.

[0004] There are three main existing methods for measuring laser angular velocity: The first is to obtain structured illumination light with a circularly symmetrical petal-like distribution through amplitude modulation. The periodic modulation of the light source amplitude will generate a specific frequency. The second, and most important, method utilizes a light source formed by the interference of beams carrying orbital angular momentum (OAM). OAM is caused by vortex phase. The two interfering beams have opposite helical properties, that is, they have topological charges with opposite signs, which will cause redshift and blueshift of the light, respectively. This differential shift will result in intensity modulation at a specific frequency. The third, and most recently proposed, method is a vector light method based on polarization control. This method uses a polarizer to orient and select vector light with a certain higher-order polarization characteristic to generate periodic intensity modulation. The specific frequency Δf generated by these three methods is the Doppler frequency shift. The angular velocity of the target object can then be calculated using the formula Δf = lΩ / 2π, where l is the number of cycles of the light intensity change and Ω is the angular velocity of the object.

[0005] For the first two methods, the magnitude of the angular velocity vector is easily detected, but the direction of the angular velocity is difficult to obtain directly unless additional techniques are used, such as dual-frequency or heterodyne interferometry, or multi-beam lasers. The third method utilizes the polarization selection of polarizers with different polarization directions in the two beams of the device to induce a Doppler phase shift in the probe light to determine the direction of motion, thus improving upon the difficulty in directly obtaining the direction of angular velocity in the first two methods. All three methods have been well validated in angular velocity measurements; however, alignment between the light source center and the target object's axis of rotation is a prerequisite for detection. In measurements where the target object completely covers the light source, within certain limits, the greater the offset between the light source center and the target object's axis of rotation, the more diffuse the resulting frequency shift becomes, even becoming submerged in noise and unmeasurable. Furthermore, when measuring the angular velocity of a tiny object smaller than the light source, since most light sources are distributed in a hollow ring, the object must be placed within the ring envelope of the light source. Therefore, the alignment problem between the light source and the target object remains a challenge that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a super-resolution angular velocity vector measurement device and method.

[0007] A super-resolution angular velocity vector measurement device, comprising:

[0008] A beam generation module, which is used to generate a special associated partially coherent beam of a coherent structure rotation;

[0009] A rotating platform on which the object to be tested is placed, wherein the coherent beam of the special associated part of the rotating coherent structure is transmitted or reflected by the object to be tested to obtain the test beam.

[0010] A detection module that limits the Rayleigh limit of the test beam and acquires the light intensity signal therein;

[0011] A computer, connected to the detection system, is used to process the obtained light intensity signal using MATLAB software to obtain the corresponding spectrum, and then calculate the angular velocity vector of the object under test, wherein the angular velocity vector includes the magnitude and direction of the angular velocity.

[0012] Preferably, the beam generating module includes:

[0013] A laser that emits a laser beam;

[0014] A beam expander, wherein the beam expander expands the laser beam;

[0015] The DMD loads a dynamically cyclic binary graph to give the expanded laser beam a special correlation structure and controls the rotation of the coherent structure to obtain a special correlation laser beam with rotating coherent structure.

[0016] A beam splitter reflects a specially correlated laser beam rotating on the coherent structure;

[0017] The 4f system performs diffraction order screening on the specially correlated laser beam rotating in the coherent structure to obtain the desired diffraction order beam;

[0018] Frosted glass, through which the diffraction-grade beam generates a special correlated incoherent light with coherent structural rotation;

[0019] A collimating lens is used to collimate the specially correlated incoherent light of the coherent structure rotation into a specially correlated partially coherent beam of the coherent structure rotation.

[0020] The DMD is loaded with any one of the following holograms: a Gaussian array, a circ function array, or a Laguerre array.

[0021] Preferably, the 4f system includes a first lens, a first aperture stop, and a second lens arranged sequentially; the first lens and the second lens form a conventional 4f system, and the aperture stop is located at the back focal plane of the first lens to allow the desired diffraction order beam to pass through.

[0022] Preferably, a reflector is provided between the 4f system and the frosted glass.

[0023] Preferably, the detection module includes:

[0024] A telecentric system for limiting the Rayleigh limit of the test beam;

[0025] The detector receives the transmitted light beam passing through the telecentric system and acquires the light intensity signal therein.

[0026] Preferably, the telecentric system includes a third lens, a second aperture, and a fourth lens arranged sequentially, with the aperture located on the spectral plane of the telecentric system.

[0027] Preferably, the detector is an electron multiplication charge-coupled device.

[0028] Preferably, the detection module includes:

[0029] A third lens, used to focus the test beam;

[0030] The second aperture, located at the rear focal plane of the third lens, is used to limit the Rayleigh limit of the test beam;

[0031] A magnified photodetector is used at any distance after the second aperture to receive light passing through the second aperture and acquire the light intensity signal therein.

[0032] A super-resolution angular velocity vector measurement method, implemented using the super-resolution angular velocity vector measurement device described above, includes:

[0033] S1: Generating a partially coherent beam with a special coherent structure for detection: The light source is expanded by a beam expander and covers the working area of ​​the DMD. The DMD is used to control the rotation of the coherent structure to obtain a laser beam with a rotating coherent structure. The laser beam with a rotating coherent structure is filtered by a 4f system to obtain the required diffraction order and hits the frosted glass. The frosted glass generates a special correlated incoherent light with a rotating coherent structure. After being collimated by a collimating lens, a partially coherent beam with a rotating coherent structure can be generated for angular velocity measurement.

[0034] S2: Use the obtained beam as a light source to detect the angular velocity vector: The coherent beam of the special associated part of the rotation of the coherent structure is incident on the object to be measured placed on the rotating platform.

[0035] S3: The light transmitted or reflected by the object under test passes through the telecentric system and is recorded by the detector as the light intensity signal of the object under test.

[0036] S4: Finally, the obtained light intensity signal is processed using MATLAB software to obtain the corresponding spectrum, and then the angular velocity vector of the object under test is calculated. The angular velocity vector includes the magnitude and direction of the angular velocity.

[0037] Preferably, the light source is a coherent lattice beam.

[0038] The technical solution of the present invention has the following advantages compared with the prior art:

[0039] The super-resolution angular velocity vector measurement device and method described in this invention allows the rotation axis of the object under test to deviate from the center of the light source and tolerate external jitter, solving the problem in existing technologies where the rotation axis of the object under test needs to be strictly aligned with the center of the light source. By tracking the rotational motion of the object under test through the coherent structure of the rotating light source, a redshift occurs when both rotate in the same direction; a blueshift occurs when they rotate in opposite directions, thus allowing simultaneous determination of the magnitude and direction of the angular velocity. By flexibly controlling the frequency shift by increasing or decreasing the beat frequency, angular velocity measurements can be achieved across a range from ultra-low speed to ultra-high speed. Attached Figure Description

[0040] 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.

[0041] Figure 1 This is a schematic diagram of the super-resolution angular velocity vector measurement device of the present invention.

[0042] Figure 2 This is a two-dimensional distribution diagram of the coherence of the light source in this invention.

[0043] Figure 3 This is a schematic diagram showing the shape and dimensions of the Arayley object of the present invention.

[0044] Figure 4 This is the experimental light intensity distribution diagram of this invention.

[0045] Figure 5 This is a frequency diagram measured when the coherent structure of the present invention rotates in the same direction as the object and in the opposite direction.

[0046] Explanation of reference numerals in the accompanying drawings: 1. Laser; 2. Beam expander; 3. DMD; 4. Beam splitter; 5. 4f system; 501. First lens; 502. First aperture; 503. Second lens; 6. Reflector; 7. Ground glass; 8. Collimating lens; 9. Rotating platform; 10. Telecentric system; 1001. Third lens; 1002. Second aperture; 1003. Fourth lens; 11. Detector; 12. Computer. Detailed Implementation

[0047] 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.

[0048] like Figure 1 As shown, the present invention proposes a super-resolution angular velocity vector measurement device, comprising:

[0049] A beam generation module, which is used to generate a partially coherent beam with a special coherent structure and rotating coherent structure;

[0050] A rotating platform 9 on which an object to be tested is placed, and a partially coherent beam with a special coherent structure is transmitted or reflected by the object to be tested to obtain a test beam.

[0051] A detection module that limits the Rayleigh limit of the test beam and acquires the light intensity signal therein;

[0052] Computer 12, connected to the detection system, is used to process the obtained light intensity signal using MATLAB software to obtain the corresponding spectrum, and then calculate the angular velocity vector of the object under test, wherein the angular velocity vector includes the magnitude and direction of the angular velocity.

[0053] In one specific embodiment, the beam generating module includes:

[0054] Laser 1, which emits a laser beam;

[0055] Beam expander 2, which expands the laser beam;

[0056] DMD3 (Digital Micromirror Devices) uses a dynamically cyclic binary graph loaded onto it to give the expanded laser beam a special correlation structure and control the rotation of the coherent structure to obtain a special correlation laser beam with rotating coherent structure.

[0057] Beam splitter 4, which reflects the special associated laser beam rotating in the coherent structure;

[0058] 4f system 5, wherein the 4f system 5 performs diffraction order screening on the special correlated laser beam rotating in the coherent structure to obtain the desired diffraction order beam;

[0059] Frosted glass 7, through which the diffraction-grade beam generates a special correlated incoherent light with coherent structural rotation;

[0060] Collimating lens 8, after collimation by the specially associated incoherent light collimating lens 8 with the coherent structure rotation, produces a specially associated partially coherent beam with the coherent structure rotation.

[0061] DMD3 contains any one of the following holograms: a Gaussian array, a circ function array, or a Laguerre array.

[0062] In one specific embodiment, the 4f system 5 includes a first lens 501, a first aperture stop 502, and a second lens 503 arranged sequentially. The first lens 501 and the second lens 503 constitute a conventional 4f system 5, and the aperture stop is located at the back focal plane of the first lens 501 to allow the desired diffraction order beam to pass through.

[0063] In an optional embodiment, to avoid the super-resolution angular velocity vector measuring device described in this embodiment occupying too long a distance, a reflector 6 is provided between the 4f system 5 and the frosted glass 7, which bends the optical path and reduces the overall length of the super-resolution angular velocity vector measuring device.

[0064] In one specific embodiment, the detection module includes:

[0065] Telecentric system 10, the telecentric system 10 being used to limit the Rayleigh limit of the test beam;

[0066] Detector 11 receives the transmitted light beam passing through the telecentric system 10 and acquires the light intensity signal therein.

[0067] In one specific embodiment, the telecentric system 10 includes a third lens 1001, a second aperture 1002, and a fourth lens 1003 arranged sequentially, with the aperture located on the spectral plane of the telecentric system 10.

[0068] In an optional embodiment, the detection module includes:

[0069] The third lens 1001 is used to focus the test beam;

[0070] The second aperture 1002 is located at the rear focal plane of the third lens 1001 and is used to limit the Rayleigh limit of the test beam.

[0071] A magnified photodetector 11 is provided, which is located at any distance after the second aperture 1002, and is used to receive the light passing through the second aperture 1002 and obtain the light intensity signal therein.

[0072] This invention also proposes a super-resolution angular velocity vector measurement method, implemented using the aforementioned super-resolution angular velocity vector measurement device, comprising:

[0073] S1: Generating a special correlated partially coherent beam for detection of coherent structure rotation: The laser 1 emits a laser beam, which is expanded by the beam expander 2 and covers the working area of ​​the DMD3. The DMD3 is used to load a special correlated structure and control the rotation of the coherent structure to obtain a special correlated laser beam with coherent structure rotation. The special correlated laser beam with coherent structure rotation is filtered by the 4f system 5 to obtain the required diffraction order and strikes the frosted glass 7. The frosted glass 7 generates special correlated incoherent light with coherent structure rotation, which is then collimated by the collimating lens 8 to generate a special correlated partially coherent beam with coherent structure rotation for angular velocity measurement.

[0074] S2: Use the obtained beam as a light source to detect the angular velocity vector: The coherent beam of the special associated part of the coherent structure rotation is incident on the object to be measured placed on the rotating platform 9;

[0075] S3: The light transmitted or reflected by the object under test passes through the telecentric system 10 and is recorded by the detector 11 as the light intensity signal of the object under test.

[0076] S4: Finally, the obtained light intensity signal is processed using MATLAB software to obtain the corresponding spectrum, and then the angular velocity vector of the object under test is calculated. The angular velocity vector includes the magnitude and direction of the angular velocity.

[0077] In this embodiment, the invention is further explained by discussing its theoretical basis. The second-order coherence phenomenon of a scalar field can be quantitatively described by the cross-spectral density function in the space-frequency domain:

[0078]

[0079] Where r n =(x n ,y n Let n = 1, 2, U represent the complex amplitude at two arbitrary positions r1 and r2 in the light field, <> represent the ensemble average, * represent the complex conjugate, I represent the light intensity at two arbitrary positions r1 and r2 in the light field, and μ(r1, r2) be the coherence degree, representing the degree of correlation between the light vibrations at any two points in space. Here, only the steady-state quasi-monochromatic coherent light is considered, therefore the angular frequency ω is ignored. A cross-spectral density function with practical physical meaning needs to satisfy the positive definite condition:

[0080] Γ(r1,r2)=∫p(v)H * (r1,v)H(r2,v)d 2 v, (2)

[0081] Where p(v) is a nonnegative function and H0(r,v) is an arbitrary kernel function. Considering a linear optical system, if the H0(r,v) function has a Fourier-like structure, then the p(v) function and the coherence μ(r1, r2) form a Fourier transform relationship. Here, the p(v) function can be understood as incoherent light with a special spatial distribution used to generate partially coherent beams.

[0082] When this beam is used to probe a transmissible object, and after passing through the 4f system 5, the cross-spectral density of the probe surface is:

[0083] Γ(u1,u2)=∫Γ(r1,r2)O * (r1)O(r2)h(r1,u1)h * (r2,u2)d 2 r1d 2 r2, (3)

[0084] Where O represents the transmittance function of the object under test, h represents the impulse function of the system, and u n =(u nx ,u ny ), where n = 1, 2 represent the coordinates of the vector at any position on the detection surface. When u = u1 = u2, Γ(u,u) is the light intensity of the detection surface.

[0085] For two object points that make any angle α with the x-axis and are separated by a distance l:

[0086]

[0087] According to equation (3), if the light source is a Sher model light source with coherence of μ(r1-r2), then its detection surface intensity is:

[0088]

[0089] Where C is a constant,

[0090] It is known that when the coherence is less than 0, the light intensity at the center of the Airy disk of two object points will be lower than that under incoherent illumination, thus breaking the classical Rayleigh limit. Therefore, the coherent structure distribution with negative intervals can be obtained by designing the p(v) function. If the coherent structure has a periodic negative interval distribution, it can be predicted that when using this type of beam to detect a Rayleigh object, the light intensity will exhibit periodic intensity modulation as the angle of the object changes linearly. From equation (5), it can be seen that the detection light intensity is directly related to the coherence, and the value of this type of coherence μ(r1-r2) is only related to the relative displacement and not to the absolute position, so the detection does not require alignment. When the object under the light source rotates, it will cause intensity modulation, corresponding to the following frequency:

[0091]

[0092] Where n is the period of change of the light intensity of the light source, and Ω1 is the angular velocity of the object under test. When the coherent structure rotates while the object under test remains stationary, the corresponding frequency is:

[0093]

[0094] Where Ω2 is the angular velocity of the light source. When the coherent structure and the object under test rotate simultaneously, beat frequency will occur.

[0095] Δf=|f1±f2|, (8)

[0096] A negative sign indicates that the light source and the object under test are rotating in the same direction, resulting in a red shift in the light beam; a positive sign indicates that the light source and the object under test are rotating in opposite directions, resulting in a blue shift in the light beam.

[0097] In a specific embodiment, a coherent lattice beam is used as the light source, and according to equation (5), its p(v) function is:

[0098]

[0099] The corresponding coherence is:

[0100]

[0101] Among them, (v x ,v yLet represent the coordinates of the vector at any position in the plane of the p(v) function, s be the distance between any two Gaussian functions in the p(v) function, w0 be the waist width of the Gaussian function, δ be the coherence length, λ be the wavelength of light, and f1 be the focal length of the lens at which the Fourier transform occurs. The two-dimensional distribution of coherence is shown in [reference needed]. Figure 2 As can be seen from the figure, this coherent structure has a periodic distribution of negative value intervals.

[0102] In the experimental setup of this embodiment, laser 1 emits a continuous wave with a wavelength λ of 532 nm. A dynamically cyclic binary map is loaded onto DMD3 to control the rotation of the coherent structure. The modulated beam is filtered by a 4f system 5 consisting of a first lens 501 and a second lens 503 with a focal length of 200 mm to obtain the desired diffraction spot. Collimating lens 8 has a focal length of 100 mm, and the object to be measured on the rotating platform 9 has a length of 40 μm and a width of 10 μm (see...). Figure 3 The third lens 1001 and the fourth lens 1003 have a focal length of 250 mm and an aperture radius of 1.5 mm, from which the Rayleigh limit of the system is calculated to be approximately 54.1 μm. The detector 11 is an electron-multiplying charge-coupled device (EMCCD). Signal processing only involves the total light intensity and not the spatial resolution; an EMCCD is used here for ease of visual observation. Figure 4 The experimental light intensity change per π / 6 when the object under test rotates 2π under the light source is shown in the figure. As can be seen from the figure, the light intensity exhibits a periodic change pattern of splitting-aggregation-splitting-aggregation.

[0103] When the rotational speed of the object under test is less than that of the coherent structure, formula (8) becomes Δf = f1 ± f2. Using the binary graph on DMD3, the rotational speed of the coherent structure is set to 5 / 18 r / s, corresponding to a frequency of 1 / 6 Hz; the rotational speed of the object under test is set to 0.1 r / s. The frequency graphs obtained when the coherent structure and the object under test rotate in the same direction and in opposite directions are shown below. Figure 5 As shown. The rotational speed of the object under test (in r / s) can be obtained from (Δf-f2) / n. A positive sign indicates that the object under test rotates in the opposite direction to the coherent structure, and a negative sign indicates that the object under test rotates in the same direction as the coherent structure. Multiple sets of experiments were conducted, and the average relative error was found to be less than 0.05%.

[0104] 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 super-resolution angular velocity vector measurement device, characterized in that, include: A beam generation module, which is used to generate a special associated partially coherent beam of a coherent structure rotation; A rotating platform on which the object to be tested is placed, wherein the coherent beam of the special associated part of the rotating coherent structure is transmitted or reflected by the object to be tested to obtain the test beam. A detection module that limits the Rayleigh limit of the test beam and acquires the light intensity signal therein; A computer, connected to the detection module, is used to process the obtained light intensity signal using MATLAB software to obtain the corresponding spectrum, and then calculate the angular velocity vector of the object under test, wherein the angular velocity vector includes the magnitude and direction of the angular velocity. The beam generating module includes: A laser that emits a laser beam; A beam expander, wherein the beam expander expands the laser beam; The DMD loads a dynamically cyclic binary graph to give the expanded laser beam a special correlation structure and controls the rotation of the coherent structure to obtain a special correlation laser beam with rotating coherent structure. A beam splitter reflects a specially correlated laser beam rotating on the coherent structure; 4 f The system, the 4 f The system performs diffraction order screening on the special correlated laser beams rotating in the coherent structure to obtain the desired diffraction order beam; Frosted glass, through which the diffraction-grade beam generates a special correlated incoherent light with coherent structural rotation; A collimating lens is used to collimate the specially correlated incoherent light of the coherent structure rotation into a specially correlated partially coherent beam of the coherent structure rotation. The DMD is loaded with any one of the following holograms: a Gaussian array, a circ function array, or a Laguerre array.

2. The super-resolution angular velocity vector measuring device according to claim 1, characterized in that, The 4 f The system includes a first lens, a first aperture, and a second lens arranged sequentially; the first lens and the second lens form a conventional 4 f The system has an aperture located at the rear focal plane of the first lens to allow the desired diffraction order beam to pass through.

3. The super-resolution angular velocity vector measuring device according to claim 1, characterized in that, The 4 f A reflector is placed between the system and the frosted glass.

4. The super-resolution angular velocity vector measuring device according to claim 1, characterized in that, The detection module includes: A telecentric system for limiting the Rayleigh limit of the test beam; The detector receives the transmitted light beam passing through the telecentric system and acquires the light intensity signal therein.

5. The super-resolution angular velocity vector measuring device according to claim 4, characterized in that, The telecentric system includes a third lens, a second aperture, and a fourth lens arranged in sequence, with the aperture located on the spectral plane of the telecentric system.

6. The super-resolution angular velocity vector measuring device according to claim 4, characterized in that, The detector is an electron multiplication charge-coupled device.

7. The super-resolution angular velocity vector measuring device according to claim 1, characterized in that, The detection module includes: A third lens, used to focus the test beam; The second aperture, located at the rear focal plane of the third lens, is used to limit the Rayleigh limit of the test beam; A magnified photodetector is used at any distance after the second aperture to receive light passing through the second aperture and acquire the light intensity signal therein.

8. A super-resolution angular velocity vector measurement method, characterized in that, This is achieved using the super-resolution angular velocity vector measurement device as described in any one of claims 1-7, comprising: S1: Generating a partially coherent beam with a special coherent structure for detection: The light source, after being expanded by a beam expander, covers the working area of ​​the DMD. The DMD is used to control the rotation of the coherent structure, resulting in a laser beam with a rotating coherent structure; the laser beam with a rotating coherent structure consists of 4... f The system selects the required diffraction order and hits it onto the frosted glass. The frosted glass generates a special correlated incoherent light with coherent structural rotation. After being collimated by the collimating lens, a special correlated partially coherent beam with coherent structural rotation for angular velocity measurement can be generated. S2: Use the obtained beam as a light source to detect the angular velocity vector: The coherent beam of the special associated part of the rotation of the coherent structure is incident on the object to be measured placed on the rotating platform. S3: The light transmitted or reflected by the object under test passes through the telecentric system and is recorded by the detector as the light intensity signal of the object under test. S4: Finally, the obtained light intensity signal is processed using MATLAB software to obtain the corresponding spectrum, and then the angular velocity vector of the object under test is calculated. The angular velocity vector includes the magnitude and direction of the angular velocity.

9. The super-resolution angular velocity vector measurement method according to claim 8, characterized in that, The light source is a coherent lattice beam.

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