CN116045815A - Wedge orthogonal laser self-mixing interference displacement detection device and method - Google Patents
Wedge orthogonal laser self-mixing interference displacement detection device and method Download PDFInfo
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- CN116045815A CN116045815A CN202211097407.1A CN202211097407A CN116045815A CN 116045815 A CN116045815 A CN 116045815A CN 202211097407 A CN202211097407 A CN 202211097407A CN 116045815 A CN116045815 A CN 116045815A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02092—Self-mixing interferometers, i.e. feedback of light from object into laser cavity
Abstract
The invention provides a device and a method for detecting the displacement of the self-mixing interference of a wedge orthogonal laser, which are used for adding the wedge into an outer cavity of a laser self-mixing interference system, so that a pair of self-mixing interference signals with phase differences can be obtained, and the phase differences can be conveniently and quickly adjusted by changing the position of a second optical wave, thereby realizing simple and convenient orthogonal displacement reconstruction and solving the problem of non-orthogonal phase errors caused by the processing precision of an optical element and the adjustment of the optical element.
Description
Technical Field
The invention relates to the technical field of precision optical interferometry, in particular to a wedge orthogonal laser self-mixing interference displacement detection device and method.
Background
The self-mixing interferometer is a single-light path interferometer integrating a light source, an interferometer and a detector. The self-mixing interference effect is a new technology with high sensitivity in the detection field, can measure various physical parameters including displacement, speed, acceleration, flow, refractive index, laser linewidth and the like, and is also applied to aspects of biological medicine, imaging and the like. When laser emitted by the laser enters the laser cavity after being reflected or scattered by an external object, self-mixing interference occurs between light in the cavity and feedback light, so that the light intensity and the wavelength of the output light of the laser are changed. Compared with the traditional interferometer principle, the two interference signal waveforms have similar shapes and identical fringe resolution, but the laser self-mixing interferometer has the advantages of simple light path, no need of additional filters and the like. However, the conventional laser self-mixing interference displacement measuring instrument needs the laser to be at a moderate optical feedback level, so that the target displacement direction is judged in advance by utilizing the inclination direction of the self-mixing interference signal, and then the phase expansion is performed to reconstruct the target displacement. The method has certain requirements on the reflection coefficient of the target surface, is not suitable for weak feedback level, cannot realize real-time reconstruction of target displacement, and cannot meet the real-time measurement requirements of the manufacturing industry under different working conditions.
In the Chinese patent of the invention of publication No. 2020.04.21: in the phase modulation type orthogonal polarization laser feedback grating interferometer and the measuring method thereof, the measuring principle is based on grating diffraction, optical Doppler effect, lamb semi-classical theory and time domain orthogonal demodulation principle. The orthogonal polarized light output by the double-refraction double-frequency helium-neon laser is vertically incident to the polarization beam splitter prism and is divided into two linearly polarized light beams with different polarization directions, and the two polarized light beams respectively pass through two different electro-optical modulators and are respectively incident to the reflection diffraction grating by the reflecting mirror at the + -1-level littrow incidence angle. The diffracted light returns to the laser cavity along the respective incident light to generate self-mixing interference with the light in the cavity. The backward output light of the laser only keeps single-mode light after passing through the polaroid and is accepted by the photoelectric detector, and the output signal of the photoelectric detector is output to the data processing module for data processing, so that the two-dimensional displacement of the target to be detected is obtained.
As shown in the above patent, the quadrature demodulation algorithm is a fast, high-sensitivity method for achieving target displacement reconstruction. However, in general, the method for constructing two paths of orthogonal self-mixing interference signals is still limited by the processing precision and the optical path adjustment of the optical element, and is easy to cause non-orthogonal phase errors, so that displacement reconstruction errors are caused. And the introduced optical elements such as the photoelectric modulator not only increase the cost of the instrument, but also cause difficulty in adjusting the instrument. Therefore, the prior art has a certain limitation, and it is a problem to be solved to study a simple optical path structure to generate two orthogonal self-mixing signals.
Disclosure of Invention
In order to solve the technical problems of non-orthogonal error, huge instrument volume, complex structure and the like of the traditional laser self-mixing interferometers based on the orthogonal demodulation algorithm, the invention provides a wedge orthogonal laser self-mixing interference displacement detection device, which adopts the following technical scheme:
the device comprises a wedge, an adjustable attenuation sheet, a laser, a first wave, a second wave, a micro platform, a signal acquisition module and a signal processing module; wherein:
the wedge, the adjustable attenuation sheet, the laser and the first light wave are sequentially and linearly arranged with the measured target to form a wedge orthogonal laser self-mixing interference light path;
the second light wave is carried on the micro-motion platform and is arranged on the reflection light path of the wedge;
the signal acquisition module is used for acquiring two paths of self-mixing interference signals with phase differences respectively emitted by the first light blade and the second light blade in the detection process and transmitting the self-mixing interference signals to the signal processing module;
the signal processing module is used for providing a driving signal for the micro-motion platform so that the second light wave moves along the radial direction of the light spot; and the method is also used for obtaining the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
Compared with the prior art, the phase difference self-mixing interference system has the advantages that the wedge is only added into the outer cavity of the laser self-mixing interference system, so that a pair of self-mixing interference signals with the phase difference can be obtained, the phase difference can be conveniently adjusted by changing the position of the second optical wave, simple and convenient orthogonal displacement reconstruction is realized, and the problem of non-orthogonal phase error caused by the processing precision of the optical element and the adjustment of the optical element is solved.
As a preferable scheme, the signal acquisition module comprises a first photoelectric detector, a second photoelectric detector and a data acquisition card; wherein:
the data acquisition card is respectively connected with the first photoelectric detector and the second photoelectric detector;
the first photoelectric detector is arranged in the emergent direction of the first light wave;
the second photoelectric detector is mounted on the micro-motion platform and arranged in the emergent direction of the second light wave.
As a preferable scheme, the wedge orthogonal displacement detection algorithm comprises an orthogonal judgment algorithm and an orthogonal demodulation algorithm.
Further, the orthogonal determination algorithm comprises the following processing procedures:
normalizing the self-mixing interference signal to construct a corresponding Lissjous figure; if the Lissjous pattern is a circle, determining that the phase difference of the self-mixing interference signal is 90 °; otherwise, the micro-motion platform is controlled by the signal processing module to enable the second light wave to move along the radial direction of the light spot until the Lissjous graph of the self-mixing interference signal is a circle, and two paths of normalized self-mixing interference signals with the phase difference of 90 degrees are obtained.
Still further, the quadrature demodulation algorithm is expressed as follows:
wherein D is m (t) represents the displacement of the object to be measured; unwrap []Representing an unwrap function; atan2 () represents an arctangent operation; lambda (lambda) 0 The output light frequency of the laser is the feedback-free output light frequency; p (P) 1 (t)、P 2 (t) is a normalized phase difference of 90 DEG self-mixing interference signal.
As a preferable scheme, the laser is a He-Ne laser with the laser wavelength of 632.8 nm.
As a preferable scheme, the signal processing module takes a LabVIEW program of a computer as a platform, and obtains the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
The invention also includes the following:
a computer storage medium having stored thereon a computer program which, when executed by a processor, performs the functions of the signal processing module of the aforementioned wedge orthogonal laser self-mixing interferometry displacement detection apparatus.
A computer device comprising a storage medium, a processor and a computer program stored in the storage medium and executable by the processor, the computer program when executed by the processor implementing the functions of the signal processing module of the aforementioned wedge orthogonal laser self-mixing interference displacement detection device.
The displacement detection method based on the wedge orthogonal laser self-mixing interference displacement detection device comprises the following steps:
s1, setting a detected target and an optical element of the wedge orthogonal laser self-mixing interference displacement detection device according to a preset optical path, so that reflected light of the detected target is fed back into a laser to form self-mixing interference;
s2, acquiring two paths of self-mixing interference signals with phase differences acquired by the signal acquisition module;
s3, judging whether the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees or not through a quadrature judging algorithm in the wedge quadrature displacement detecting algorithm, and if not, driving the micro-motion platform to enable the second light wave to move along the radial direction of the light spot until the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees;
s4, obtaining the displacement of the measured target by the self-mixing interference signal according to an orthogonal demodulation algorithm in the wedge orthogonal displacement detection algorithm.
Drawings
FIG. 1 is a simplified diagram of a wedge orthogonal laser self-mixing interference displacement detection device according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of an equivalent F-P model including a wedge;
fig. 3 is a schematic flow chart of a method for detecting the self-mixing interference displacement of the wedge orthogonal laser provided in embodiment 4 of the present invention;
FIG. 4 is a graph showing the measurement result of arbitrary waveform displacement of the measured object in example 4 of the present invention;
FIG. 5 is a graph showing the measurement result of the displacement of the measured object by 20m in example 4 of the present invention;
reference numerals illustrate: 1. a laser; 2. a first light wave in combination with a first photosensor; 3. a second light wave, a second photosensor and a micro-motion platform; 4. a target to be measured; 5. wedge; 6. a target driver to be measured (displacement for generating a target to be measured in an experiment); 7. a data acquisition card; 8. a signal processing module (computer); the thick line arrows in fig. 1 represent light rays, and the thin line arrows represent signals.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the present patent;
it should be understood that the described embodiments are merely some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the embodiments of the present application, are within the scope of the embodiments of the present application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the accompanying claims. In the description of this application, it should be understood that the terms "first," "second," "third," and the like are used merely to distinguish between similar objects and are not necessarily used to describe a particular order or sequence, nor should they be construed to indicate or imply relative importance. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
Furthermore, in the description of the present application, unless otherwise indicated, "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship. The invention is further illustrated in the following figures and examples.
In order to solve the limitations of the prior art, the present embodiment provides a technical solution, and the technical solution of the present invention is further described below with reference to the drawings and the embodiments.
Example 1
Referring to fig. 1, a device for detecting the displacement of the self-mixing interference of the orthogonal laser beam of the wedge includes a wedge, an adjustable attenuation sheet, a laser, a first beam, a second beam, a micro-motion platform, a signal acquisition module and a signal processing module; wherein:
the wedge, the adjustable attenuation sheet, the laser and the first light wave are sequentially and linearly arranged with the measured target to form a wedge orthogonal laser self-mixing interference light path;
the second light wave is carried on the micro-motion platform and is arranged on the reflection light path of the wedge;
the signal acquisition module is used for acquiring two paths of self-mixing interference signals with phase differences respectively emitted by the first light blade and the second light blade in the detection process and transmitting the self-mixing interference signals to the signal processing module;
the signal processing module is used for providing a driving signal for the micro-motion platform so that the second light wave moves along the radial direction of the light spot; and the method is also used for obtaining the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
Compared with the prior art, the phase difference self-mixing interference system has the advantages that the wedge is only added into the outer cavity of the laser self-mixing interference system, so that a pair of self-mixing interference signals with the phase difference can be obtained, the phase difference can be conveniently adjusted by changing the position of the second optical wave, simple and convenient orthogonal displacement reconstruction is realized, and the problem of non-orthogonal phase error caused by the processing precision of the optical element and the adjustment of the optical element is solved.
Specifically, in fig. 1, reference numeral 1 denotes a laser; reference numeral 2 is a combination of a first photoelectric sensor and a first light wave; reference numeral 3 is a combination of a second photoelectric sensor and a micro-motion platform; reference numeral 4 is a target to be measured; reference numeral 5 is a wedge; reference numeral 6 is a target drive to be measured (displacement for generating a target to be measured in an experiment); reference numeral 7 is a data acquisition card; reference numeral 8 is a signal processing module (computer); the thick line arrows represent light rays and the thin line arrows represent signals.
The first light wave is arranged at the back of the laser; during operation, the apertures of the first and second billows are adjusted to be minimum, and are respectively positioned at the very center of the laser spot. The measured target feeds back the laser output light to the laser cavity to form self-mixing interference. And the optical paths of the feedback light are different due to the fact that the positions of the light rays irradiated to the first light wave and the second light wave passing through the wedge are different, so that two paths of laser self-mixing interference signals with phase difference are obtained.
As a preferred embodiment, the signal acquisition module comprises a first photoelectric detector, a second photoelectric detector and a data acquisition card; wherein:
the data acquisition card is respectively connected with the first photoelectric detector and the second photoelectric detector;
the first photoelectric detector is arranged in the emergent direction of the first light wave;
the second photoelectric detector is mounted on the micro-motion platform and arranged in the emergent direction of the second light wave.
As a preferred embodiment, the wedge orthogonal displacement detection algorithm includes an orthogonal decision algorithm and an orthogonal demodulation algorithm.
Further, the orthogonal determination algorithm comprises the following processing procedures:
normalizing the self-mixing interference signal to construct a corresponding Lissjous figure; if the Lissjous pattern is a circle, determining that the phase difference of the self-mixing interference signal is 90 °; otherwise, the micro-motion platform is controlled by the signal processing module to enable the second light wave to move along the radial direction of the light spot until the Lissjous graph of the self-mixing interference signal is a circle, and two paths of normalized self-mixing interference signals with the phase difference of 90 degrees are obtained.
Still further, the quadrature demodulation algorithm is expressed as follows:
wherein D is m (t) represents the displacement of the object to be measured; unwrap []Representing an unwrap function; atan2 () represents an arctangent operation; lambda (lambda) 0 The output light frequency of the laser is the feedback-free output light frequency; p (P) 1 (t)、P 2 (t) is a normalized phase difference of 90 DEG self-mixing interference signal.
Specifically, the quadrature demodulation algorithm is implemented by using the two paths of normalized self-mixing interference signals P with 90 DEG phase difference 1 (t)＝cos(x F (t)) and P 2 (t)＝sin((x F (t)) first division and then arctangent operation atan2 (P) 2 (t)/P 1 And (t)), finally, performing phase expansion by using an unwrap function, and multiplying lambda/4 pi, thereby obtaining the displacement of the measured target.
Next, the technical scheme of the present invention will be further described in principle:
as shown in fig. 2, a wedge is placed in the external cavity of the laser. According to the three-mirror cavity F-P theoretical model, the laser end face M1, the wedge and the measured object can be regarded as an equivalent mirror, so that an equivalent F-P theoretical model is formed. The reflection coefficient of the equivalent mirror can be obtained as follows:
wherein: l (L) w Is the geometric length of light passing through the wedge, L is the length from the laser end face to the measured objectDistance n 0 ,n w ,n D Refractive index, r, of the laser outer cavity, wedge and laser inner cavity, respectively 2 And r 2ext Is the reflection coefficient of the laser end face M2 and the measured object, t w Is the transmittance of the wedge.
The phase equation of the laser self-mixing interferometry system containing the cleaved tip is available as follows:
x F ＝x 0 -C sin(x F +atanα) (2)
wherein:
the laser output light power of the laser self-mixing interference system comprising the wedge is changed into:
wherein: kappa (kappa) ext ＝(1-r 2 2 )t w 2 r 2ext /r 2 The coupling coefficient of the optical feedback of the external cavity comprising the wedge, D (t) is the displacement of a measured target, C is an optical feedback level parameter, and the refractive index of the external cavity is set to n0=1; lambda (lambda) F And lambda (lambda) F The output light frequency of the laser is respectively the light feedback and the no feedback, and the system is kept to work under the mechanism of weak light reflection level C<0.1, lambda F ≈λ 0 。
When the wedge angle theta is small, the distance difference between the two light beams passing through the first and second light blades in the wedge is
Wherein: r is the distance from the second wave to the centre of the spot.
Thus, two paths of self-mixing interference signals with phase difference obtained by the first photodetector and the second photodetector can be expressed as:
obtainable P 1 (t) and P 2 The phase difference of (t) is
From the equation (9), by moving the micro-motion stage, the distance r from the second wave to the center of the light spot is changed to obtain a pair of self-mixing interference signals P with 90 DEG phase difference 1 (t) and P 2 (t) making P 1 (t)＝cos(x F (t)) and P 2 (t)＝sin((x F (t))。
The displacement of the measured target is as follows according to the quadrature demodulation algorithm
As a preferred embodiment, the laser is a He-Ne laser with a laser wavelength of 632.8 nm.
As a preferred embodiment, the signal processing module takes LabVIEW program of a computer as a platform, and obtains the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
Example 2
A computer storage medium having stored thereon a computer program which, when executed by a processor, performs the function of the signal processing module of the split orthogonal laser self-mixing interferometry displacement detection apparatus of embodiment 1.
Example 3
A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable by the processor, the computer program when executed by the processor implementing the functions of the signal processing module of the split orthogonal laser self-mixing interferometry displacement detection apparatus of embodiment 1.
Example 4
Referring to fig. 3, a displacement detection method implemented by the wedge orthogonal laser self-mixing interference displacement detection device according to embodiment 1 includes the following steps:
s1, setting a detected target and an optical element of the wedge orthogonal laser self-mixing interference displacement detection device according to a preset optical path, so that reflected light of the detected target is fed back into a laser to form self-mixing interference;
s2, acquiring two paths of self-mixing interference signals with phase differences acquired by the signal acquisition module;
s3, judging whether the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees or not through a quadrature judging algorithm in the wedge quadrature displacement detecting algorithm, and if not, driving the micro-motion platform to enable the second light wave to move along the radial direction of the light spot until the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees;
s4, obtaining the displacement of the measured target by the self-mixing interference signal according to an orthogonal demodulation algorithm in the wedge orthogonal displacement detection algorithm.
The scheme of the invention will be further described in connection with specific experiments:
He-Ne with wavelength of 632.8nm is selected as laser source, and the measured object is subject to arbitrary waveform motion, and its displacement waveform is D (t) = [1+10sin (2pi f) 0 t)]×A 0 sin(2πf 0 t), wherein A 0 =0.10 μm, frequency f 0 ＝10Hz。
As shown in fig. 4, the target displacement can be directly reconstructed without target direction recognition at a weak feedback level, and the maximum absolute error is 50nm for any vibration of the target with a maximum displacement amplitude of 1.1 μm.
As shown in FIG. 5, the target motion was shifted by 20. Mu.m, the maximum absolute error was 182nm, and the relative error was 0.91%. As is obvious from the figure, the device and the method for detecting the self-mixing interference displacement of the wedge orthogonal laser can still well realize the measurement of the target displacement even if the signal contains speckle noise introduced by the target large displacement.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. The device is characterized by comprising a wedge, an adjustable attenuation sheet, a laser, a first light wave, a second light wave, a micro-motion platform, a signal acquisition module and a signal processing module; wherein:
the wedge, the adjustable attenuation sheet, the laser and the first light wave are sequentially and linearly arranged with the measured target to form a wedge orthogonal laser self-mixing interference light path;
the second light wave is carried on the micro-motion platform and is arranged on the reflection light path of the wedge;
the signal acquisition module is used for acquiring two paths of self-mixing interference signals with phase differences respectively emitted by the first light blade and the second light blade in the detection process and transmitting the self-mixing interference signals to the signal processing module;
the signal processing module is used for providing a driving signal for the micro-motion platform so that the second light wave moves along the radial direction of the light spot; and the method is also used for obtaining the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
2. The wedge orthogonal laser self-mixing interference displacement detection device according to claim 1, wherein the signal acquisition module comprises a first photoelectric detector, a second photoelectric detector and a data acquisition card; wherein:
the data acquisition card is respectively connected with the first photoelectric detector and the second photoelectric detector;
the first photoelectric detector is arranged in the emergent direction of the first light wave;
the second photoelectric detector is mounted on the micro-motion platform and arranged in the emergent direction of the second light wave.
3. The device for detecting the displacement of the self-mixing interference of the split orthogonal laser according to claim 1, wherein the detection algorithm of the displacement of the split orthogonal laser comprises an orthogonal judgment algorithm and an orthogonal demodulation algorithm.
4. The device for detecting the displacement of the self-mixing interference of the wedge orthogonal laser according to claim 3, wherein the orthogonal judging algorithm comprises the following processing procedures:
normalizing the self-mixing interference signal to construct a corresponding Lissjous figure; if the Lissjous pattern is a circle, determining that the phase difference of the self-mixing interference signal is 90 °; otherwise, the micro-motion platform is controlled by the signal processing module to enable the second light wave to move along the radial direction of the light spot until the Lissjous graph of the self-mixing interference signal is a circle, and two paths of normalized self-mixing interference signals with the phase difference of 90 degrees are obtained.
5. The device for detecting the self-mixing interference displacement of the cleaved orthogonal laser according to claim 4, wherein the orthogonal demodulation algorithm is expressed by the following formula:
wherein D is m (t) represents the subjectTarget displacement; unwrap []Representing an unwrap function; atan2 () represents an arctangent operation; lambda (lambda) 0 The output light frequency of the laser is the feedback-free output light frequency; p (P) 1 (t)、P 2 (t) is a normalized phase difference of 90 DEG self-mixing interference signal.
6. The device for detecting the displacement of the self-mixing interference of the split orthogonal laser according to claim 1, wherein the laser is a He-Ne laser with a laser wavelength of 632.8 nm.
7. The device for detecting the displacement of the wedge orthogonal laser self-mixing interference according to claim 1, wherein the signal processing module takes a LabVIEW program of a computer as a platform, and obtains the displacement of the measured target from the self-mixing interference signal through a wedge orthogonal displacement detection algorithm.
8. A computer storage medium having stored thereon a computer program which, when executed by a processor, performs the function of the signal processing module of the wedge orthogonal laser self-mixing interferometry displacement detection apparatus according to any one of claims 1 to 7.
9. A computer device, characterized by: comprising a storage medium, a processor, and a computer program stored in the storage medium and executable by the processor, which when executed by the processor, performs the function of the signal processing module of the wedge orthogonal laser self-mixing interferometric displacement detection device of any one of claims 1 to 7.
10. A displacement detection method based on the wedge orthogonal laser self-mixing interference displacement detection device according to claims 1 to 7, characterized by comprising the following steps:
s1, setting a detected target and an optical element of the wedge orthogonal laser self-mixing interference displacement detection device according to a preset optical path, so that reflected light of the detected target is fed back into a laser to form self-mixing interference;
s2, acquiring two paths of self-mixing interference signals with phase differences acquired by the signal acquisition module;
s3, judging whether the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees or not through a quadrature judging algorithm in the wedge quadrature displacement detecting algorithm, and if not, driving the micro-motion platform to enable the second light wave to move along the radial direction of the light spot until the phase difference of the two paths of self-mixing interference signals with the phase difference is 90 degrees;
s4, obtaining the displacement of the measured target by the self-mixing interference signal according to an orthogonal demodulation algorithm in the wedge orthogonal displacement detection algorithm.
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