CN115900536A - Wave front dividing type one-way orthogonal light path interferometer - Google Patents

Abstract

The invention discloses an interferometer device which is formed by dividing a wave front, transmitting a reference beam and a measuring beam in a single path and then combining the beams in a positive mode, and relates to the field of precision measurement and interferometry.

Description

Wave front division type one-way orthogonal light path interferometer

Technical Field

The invention belongs to the field of photoelectric detection and measurement equipment, and particularly relates to a wavefront segmentation interferometer, a dual-frequency laser interferometer, a multi-frequency laser interferometer, a white light interferometer and a white laser interferometer.

Background

The interference principle of electromagnetic wave can be used for manufacturing a detection instrument with very high precision, and various interferometers which are commercialized at present play a significant role in the development of modern science and technology due to excellent performance in the aspects of laser gyroscopes, wavelength measurement, laser interference distance measurement, refractive index measurement and the like. According to different design ideas, principles and purposes, the conventional interferometers mainly comprise a michelson interferometer, a mach-zehnder (MZ) interferometer, a segregant interferometer, a thin-film interferometer, a fresnel double-sided mirror interferometer and the like. However, with the development of science and technology, in some fields requiring high precision, measurement of optical anisotropic materials, etc., the interferometer cannot meet the measurement requirements. The main reason is that the interferometers are limited by a structure with a double-stroke reciprocating or closed path except a few interferometers such as Fresnel double-sided mirrors; however, the interferometer such as a fresnel double-sided mirror has the disadvantages of complex structure of the combined system, difficult mathematical modeling, low comprehensive precision and the like due to the fact that the traveling wave path does not adopt orthogonal transformation, and is not beneficial to measuring and analyzing the optical anisotropy parameters of the measured object. Therefore, the wave front segmentation interferometer designed by the optical path with the one-way orthogonal structure is designed by the inventor of the invention, and can be used for the aspects of optical anisotropic medium characteristic measurement, field distribution, motion state detection, fluid analysis and the like.

Disclosure of Invention

The invention designs a wave front dividing type one-way orthogonal light path interferometer, which is based on the wave front dividing of electromagnetic wave taking the wave front as a plane, the one-way transmission of the traveling wave path, the orthogonal turning of the turning traveling wave path and the light path structure composition of combining two beams of light in the orthogonal direction (when an array type image sensor is used as an interference result detector, the turning angle of an effective reference beam is not particularly limited, even if the turning range of the effective reference beam does not exceed 90 degrees +/-1 degrees, when the light path turning structure design of a pure reflecting mirror is used, the turning angle of a beam combining mirror does not exceed 90 degrees +/-5 degrees), and the traveling wave paths of the divided reference beam and a measuring beam are not closed in space. It can be used for detecting the transmission characteristics of optical medium and field substance with optical anisotropy, and has a certain detection capability for directional moving field or fluid, mechanical movement or vibration, etc.

Specifically, the present invention provides 3 basic design architectures, which are:

a wave front division type one-way orthogonal light path interferometer device designed based on a 2D structure (see figure 1), the method is characterized in that parallel light with a wave front being a plane wave is used as a light source (1), the wave front is divided to enter a reference beam channel and a measuring beam channel respectively, a light beam of the reference beam channel enters an effective reference beam working area after passing through a light delayer (11), a light beam of the measuring beam channel enters an effective measuring working area after passing through a 90-degree light path deflector (12), the positions and postures of the light delayer (11) and the light path deflector (12) are adjusted to ensure that the axial leads (17, 18) of the two beams of light entering the effective area are orthogonal to the reflecting film layer of the half-mirror (13) for beam combination, and the included angles (theta 12, theta 13) with the surface of the reflecting film layer are both 45 degrees (a non-coplanar beam combination mode of theta 12+ theta 13=90 degrees designed according to the optical characteristics of the existing half-mirror), and the beam axis length Lr of the effective reference beam working area is equal to the beam axis length Lm of the effective measurement working area by adjusting, the time of the same wave front emitted by a light source reaching the half-transmitting half-reflecting mirror in the initial state is the same by adjusting the delay amount of the optical delayer (the same time can be obtained by the half-transmitting half-reflecting mirror without requiring the complete same time phase, and the phase deviation caused by the assembly error can be calibrated by the initialization test without strictly limiting the space-time position of 0-level interference), and the combined interference light beam is measured by an interference result detector (14) to obtain the phase difference of the reference light beam and the measurement light beam; in the scheme, if the front space and the rear space of the optical delayer have the same light propagation characteristics, no special restriction is imposed on the front position and the rear position of the optical delayer in the path of the reference light beam, the attached drawings are only convenient for calculation and understanding and do not serve as necessary limiting conditions, but the time increment of the light beam passing through the delayer (relative to the optical isotropic medium) when the light beam passes through the delayer in the optical isotropic medium and the device and the medium are in a static state is equal to the time consumed when the light beam passes through the length Lm.

A wave front division type one-way orthogonal light path interferometer device (see figures 2-4) designed based on a 3D structure is characterized in that parallel light with a wave front being a plane wave is used as a light source, the wave front is divided to enter a reference beam channel and a measuring beam channel respectively, light beams of the reference beam channel enter an effective reference beam working area after passing through a 90-degree light path turning device (21), light beams of the measuring beam channel enter an effective measuring working area after passing through a 90-degree light path turning device (22), the position and the posture of the light path turning device (21, 22) are adjusted to enable the axial leads (27, 28) of the two light beams entering the effective area to be orthogonal to a reflecting film layer of a half-reflecting mirror (23) to carry out beam combination, and the included angles (theta 21, theta 22) of the reflecting film layer are equal to 45 (a theta 12+ theta 13 + 90-degree different beam combination mode designed according to the optical characteristics of the existing half-reflecting mirror) is adopted), meanwhile, the phase difference of the axial leads the measuring beam length L21 of the effective reference beam working area and the effective beam L22 to be equal to the measuring beam length L24 of the light beams after passing through a detector, and the measuring beam phase difference of the measuring beam is obtained.

On the basis of the 2 nd implementation scheme, the half-mirror (23) is replaced by a front surface reflector (33), and the effective measuring beam moves for a certain distance in the axial lead direction and rotates for a certain angle, so that the effective reference beam and the effective measuring beam are directly combined and interfered on the interference result detector. The semi-transparent semi-reflecting mirror can be replaced by two independent front surface reflecting mirrors to respectively carry out secondary turning on the effective reference beam and the effective measuring beam, the turning vector does not have the traveling wave direction of the effective measuring beam, and the turning angle of the effective measuring beam needs to be 90 degrees so as to simplify the difficulty of post data processing.

In the three basic schemes, the interference result detector can be any device which can be used for interference result measurement, such as an image screen, frosted glass, a photoelectric detector, an image sensor and the like; preferably, a photoelectric detector or an array image sensor is used to convert the phase difference signal of the reference beam and the measuring beam into an electrical signal, so that the electrical signal can be processed and sampled by the existing traditional circuit and then sent to an electronic computer for computational analysis. When the interference result detector is an array image sensor, the light receiving surface of the image sensor and the combined interference optical wavefront need to be adjusted to be in an attitude which is not strictly parallel, or the wavefront of the effective reference beam needs to be adjusted to be in an attitude which is not strictly vertical to the wavefront of the effective measuring beam, so that the interference result of more than 0 level can be obtained.

In the three basic schemes, the spectral components of the collimated light source with the wave front being the plane wave can be single-frequency laser, monochromatic light, white laser, dual-frequency or multi-frequency laser, and dual-color or multi-color spontaneous emission light. For measuring the stability and accuracy of the result, it is preferable to use polychromatic light as the light source, and obtain more stable and accurate result and larger measuring range by detecting the displacement of 0-order interference on the interference result detector, or the phase shift fractional part of each frequency point to simultaneously solve the phase shift value of the combined frequency (see Tilford C. Analytical procedure for determining length hs from 2-dimensional waves [ J ]. Applied Optics, 1987, 16 (7)); in addition to using wave front division method to obtain coherent light, it also can use two lasers with same frequency or stable frequency difference and frequency difference not exceeding 100MHZ as light source of effective reference beam and light source of effective measuring beam respectively, and can replace parallel light source, optical delayer and optical path turning device of the above-mentioned scheme, and can respectively retain the direction and length of effective reference beam and effective measuring beam and implement detection result with same technical index.

In the three basic schemes, the light path turning device and the half-transmitting and half-reflecting mirror can be arranged on a moving mechanism which can move back and forth along the axial lead direction of the effective light beam, so that the device has the capacity of measuring the space wavelength.

In the above schemes 1 and 2, a set of auxiliary detectors can be installed on the traveling wave light path of the secondary light beam after the semi-transparent and semi-reflective mirrors are combined coherently to measure the beam directions and spectral components of the reference light beam and the measuring light beam, and the measured beam directions and spectral components are used as reference signals for automatic calibration, vibration measurement, assembly error correction and parameter drift; the reference light beam and the measuring light beam are focused and imaged, the light beam direction is detected by using the planar array type image sensor, the method can be used for tracking sunlight or starlight, and the sunlight or the starlight replaces a parallel light source in the method, so that higher-precision measurement can be realized (because the measurement precision is in direct proportion to the length of the effective measuring light beam, a light source integrated by the system is difficult to realize large light beam diameter and small wavefront distortion).

A typical method of using a wavefront-dividing type single-pass orthogonal optical path interferometer is a method in which the initial phase difference of a device is read in advance, then the phase difference between an effective reference beam and an effective measurement beam is made different from the initial state by filling or installing an anisotropic light propagation medium to be measured in the effective reference working area and the effective measurement working area, or filling a field material having an optically isotropic light propagation medium but the interferometer is moving or vibrating in a direction or having a change in the effective measurement working area, and the medium anisotropy parameter, the motion or vibration parameter, the field material structure and the form are obtained by capturing the amount of change in the phase difference. When motion and vibration detection is performed, the attitude of the interferometer should be adjusted so that the vector of the effective measuring beam remains parallel to the motion or vibration vector.

In the invention, the space area through which the reference beam passes after passing through the optical path turning device or the optical delayer before interfering the combined beam is called an effective reference beam working area, and the section of the beam is called an effective reference beam; the two beam work areas are collectively referred to as an effective work area, and the two beams are collectively referred to as an effective beam. Also as used herein, terms of mathematical or geometric relationships (e.g., plane wave, orthogonal, parallel, simultaneous, equal, 8230; etc.) are measured by engineering practice criteria and are not ideal mathematical or geometric relationships without any deviation, as long as the resolution is generally more than twice that of the particular device or component of interest. The initial state is not particularly limited in the present invention, since different test objects require different initial states to achieve the most suitable results, but there are also measurements that require a defined initial state, such as fluid measurements or motion/vibration measurements, which is either static or optimal in the case where the variable is an independent or common mode component for the effective reference beam and the effective measurement beam.

Drawings

FIG. 1 is a schematic diagram of a front view of an embodiment of a wavefront-splitting single-pass orthogonal path interferometer designed based on a 2D structure;

FIG. 2 is a schematic diagram of a top view of an embodiment of a wavefront-splitting single-pass orthogonal path interferometer designed based on a 3D architecture;

FIG. 3 is a schematic diagram of an oblique view of an embodiment of a wavefront-splitting single-pass orthogonal path interferometer designed based on a 3D structure;

FIG. 4 is a parametric illustration of an embodiment of a wavefront-splitting single-pass orthogonal path interferometer designed based on a 3D structure;

FIG. 5 is a schematic top view of an embodiment of a wavefront-splitting single-pass orthogonal path interferometer based on a 3D design and using a front surface mirror for coherent beam combining.

In fig. 1: 1) A collimated light source; 11 A light delayer; 12 A measuring beam front surface mirror; 13 A semi-transmissive semi-reflective coherent beam combiner; 14 ) an interference result detector; 15 ) an auxiliary detector; 16 A reference wavefront position of the parallel light; 16-1) a segmented reference beam axis; 16-2) the segmented measuring beam axis; 17 The axis of the effective reference beam; 18 Effectively measuring the axis of the beam; 19 Main beam axis after coherent combining; 10 ) the axes of the coherently combined secondary beams.

In FIGS. 2 to 4: 2) A collimated light source; 21 A reference beam front surface mirror; 22 A measuring beam front surface mirror; 23 A semi-transmissive semi-reflective coherent beam combiner; 24 ) an interference result detector; 25 ) an auxiliary detector; 26 ) a reference wavefront location of the parallel light; 26-1) a segmented reference parallel beam axis; 26-2) a segmented measuring parallel beam axis; 27 The axis of the effective reference beam; 28 Effective measuring the axis of the beam; 29 Main beam axis after coherent combining; 20 ) the axes of the coherently combined secondary beams.

In fig. 5: 2) A collimated light source; 21 A reference beam front surface mirror; 22 A measuring beam front surface mirror; 33 Front surface reflective beam combiner; 24 An interference result detector; 26) A reference wavefront location of the parallel light; 26-1) a segmented reference parallel beam axis; 26-2) the divided measuring parallel beam axial leads; 27 The axis of the effective reference beam; 28 Effectively measuring the axis of the beam; 29 The axis of the effective reference beam of the interference region.

Detailed Description

Based on the invention content and the realization principle, the specific implementation mode respectively adopts the following steps according to different structural designs:

1. the implementation mode of the wave front segmentation type one-way orthogonal light path interferometer designed based on the 2D structure is as follows:

according to the schematic diagram shown in FIG. 1, selecting a parallel light source as a light source (1) after a parallel light source is used as a basis of an argon ion multi-spectral line laser and parallel light beam expansion is carried out to reach the diameter of 100 mm; selecting an ultra-low dispersion glass column with the refractive index of 1.43 and the length of 100mm as a light delayer (11), carrying out fine grinding and polishing on two light passing surfaces of the glass column, and plating a visible light antireflection film; selecting a silvered front surface reflector as a light path diverter (12), and selecting an optical adjusting frame arranged on a 45-degree inclined plane as an installation base; selecting a glass-semitransparent and semi-reflecting film-glass sandwich structure as a semitransparent and semi-reflecting coherent beam combining mirror (13), wherein the thicknesses and the materials of the glass on two sides of the semitransparent and semi-reflecting film are the same, the outer side surface of the semitransparent and semi-reflecting film is plated with an antireflection film, the optimal designed incident angle of the semi-reflecting mirror is 45 degrees, and an optical adjusting frame installed on a 45-degree inclined plane is selected as an installation foundation; a surface array type color industrial camera is selected as an interference result detector (14), besides, a rutile glass slide with high dispersion rate is prepared for adjusting dispersion generated by a light delayer (11), and a base station which is customized and processed to conform to the schematic diagram layout is used as the basis for mounting each component and assembly, wherein the mounting parameters to be ensured are as follows: the two light-passing surfaces of the light delayer (11) are parallel to the wave front emitted by the light source, the front surface of the light path deflector (12) is 45-degree to the wave front emitted by the light source [ the included angle theta 11 between the axial line of the incident light beam and the axial line of the reflected light beam is equal to 90 degrees in the attached figure 1 ], the included angle theta 12 between the reflection film surface of the semi-transparent and semi-reflective beam combiner (13) and the light-passing surface of the light delayer (11) and the included angle theta 13 between the front surface of the light path deflector (12) are 45-degree, the center distance Lr from the light-emitting surface of the light delayer (11) to the semi-transparent and semi-reflective mirror is about 43mm, and the center Lm between the front surface of the light path deflector (12) and the center of the semi-transparent and semi-reflective mirror is about 43 mm.

Further, after all the parts and components are installed in place, the whole device is placed in a darkroom; connecting an output video of the industrial camera to a computer, and starting preview management software of the industrial camera; starting a parallel light source, observing whether interference fringes on a computer screen are equal-thickness interference fringes or not, and ensuring that the fringe spacing is proper so as to conveniently identify the distribution position of each chromatographic interference fringe, and if not, adjusting an optical adjusting frame for installing a light path turning device (12) and a semi-transparent semi-reflective coherent beam combiner (13) to ensure that the optical adjusting frame meets the conditions; whether interference fringes are blue or green edged and bright and clear interference fringes or not is searched, the proportion of Lm and Lr is gradually changed by adjusting a mounting seat of a half-transmitting and half-reflecting mirror or a front surface reflecting mirror to search, if the interference fringes cannot be found, a rutile glass slide prepared in advance is required to be used for compensation, the specific compensation method is that a wave front surface is parallel to a light passing surface of the glass slide, the glass slide is placed at a position, close to a light source, of a measuring light beam working area, then the search is continued through the method, and when the interference fringes without edges cannot be found, the included angle between the light passing surface of the glass slide and the wave front is rotated slowly, and the steps are repeated until the fringes appear, so that the initial adjustment is completed. The purpose of searching the interference fringes without the rims is to calibrate the measurement, namely the initial position of 0-order interference, and besides, the 0-order interference fringes are also one of efficient adjustment methods for converting laser source light into non-laser source manufacturing processes on the photosensitive surface of the camera.

Finally, the interference device is placed and fine-tuned properly so as to read a proper 0-level interference fringe initial position, then a sample is filled in an effective working area, or the posture of the device is adjusted so that an equal-intensity surface of a measured field is parallel to an effective measuring beam wave front, or a measured motion vector is parallel to an effective measuring beam axis, then the change condition of the position of the interference fringe without an edge is recorded again to calculate the displacement of 0-level interference, and the mapping relation between the displacement and the measured physical quantity is analyzed according to a physical association mathematical formula of the measured physical quantity and the displacement, so that the purpose of measurement is realized. Preferably, the mathematical formulas of these physical associations should be programmed into an application for automated calculations and output of various relevant reports.

The foregoing detailed description is only for the purpose of understanding the installation method, parameters and implementation steps of the exemplary embodiment device 1, and is not intended to limit the invention, and those skilled in the art should be able to make flexible configuration and implementation by using the implementation method and implementation principle described in the disclosure of the present invention and the well-known technology.

The implementation mode of the wave front segmentation type one-way orthogonal light path interferometer based on the 3D structure design comprises the following steps:

according to the schematic diagrams shown in fig. 2 to 4, selecting a parallel light source as a disc laser and carrying out nonlinear frequency doubling to generate a multispectral laser as a light source; selecting a silvered front surface reflector as a light path diverter (21, 22), and respectively selecting an optical adjusting frame arranged on a 45-degree inclined plane as an installation base; selecting a semi-transparent and semi-reflective cube as a coherent beam combining mirror (23), wherein four light transmission surfaces of the semi-transparent and semi-reflective cube are plated with antireflection films, the light transmission surfaces of the light cube are in parallel relation with wave surfaces corresponding to incident/emergent light, the mounting direction of the light cube is to ensure that the vector of the reflected light is the same as that of the emergent light of another effective light beam, and an optical adjusting frame which does not shield the four light transmission surfaces is selected as a mounting base for the light cube; selecting a multi-path photodetector with wavelength division demultiplexing as an interference result detector (24); selecting an auxiliary detector (25) with an internal light splitting device and an imaging lens for beam inclination measurement and spectral measurement; in addition, a customized base station which is in accordance with the layout of the schematic diagram is used as the basis for mounting each component and assembly, wherein the mounting parameters which need to be ensured respectively comprise: the front surfaces of the optical path inflators (21, 22) are in a 45-degree relationship with the emitted wave front of the light source, and the two emitted light beam axes after passing through the optical path inflector are in an orthogonal relationship [ implicitly, the intersection line between the wave front and the reflection surface when passing through the intersection point of the incident-reflected light beam axes and the axes of the two beams are in an orthogonal relationship of 90 degrees, i.e. θ 27 and θ 28 are 90 degrees in fig. 4 ], the angle θ 21 between the reflection film surface of the coherent beam combiner (23) and the effective reference light beam axis and the angle θ 22 between the effective measurement light beam axes are in an orthogonal beam combining manner of 45 degrees (θ 12+ θ 13=90 degrees according to the optical characteristics of the existing half-mirror, see the notation of fig. 4), the angles between the intersection line of the respective wave front and the reflection film and the respective axes are 90 degrees with respect to the respective axes < θ 23, θ 24>, the relationship implies that the effective reference light beam length L21 is equal to the effective measurement axis L =38.5mm in the present embodiment.

Further, after all the components and assemblies are installed in place, the whole device is placed in a darkroom; connecting each output of the interference result detector (24) to a multi-channel phase meter; and starting the parallel light source, respectively recording phase initial values after phase indication values of all paths of photoelectric detectors of the interference result detector (24) are stable, and solving phase values of the composite frequency in parallel.

Finally, the sample is filled in an effective working area or the posture of the device is adjusted to enable the equal-intensity surface of the measured field to be parallel to the wave front of the effective measuring beam or the measured motion vector to be parallel to the axial lead of the effective measuring beam, then the phase indication value or the frequency shift value of each path of photoelectric detector is recorded again, the phase value of the sum frequency is solved through simultaneous solving, and then the mapping relation between the phase variation or the frequency variation and the measured physical quantity is solved according to the measured and the physical associated mathematical formula thereof, so that the purpose of measurement is realized. Preferably, the mathematical formulas of these physical associations should be compiled into an application program for automated calculations and output of various relevant reports.

The foregoing detailed description is only for the understanding of the installation method, parameters and implementation steps of the exemplary embodiment device 2, and is not intended to limit the invention, and those skilled in the art should be able to make flexible configuration and implementation by using the implementation method and implementation principle described in the disclosure of the present invention and well-known technology.

The implementation mode of the wave front segmentation type one-way orthogonal light path interferometer for coherent beam combination by adopting a front surface reflector based on 3D structure design is as follows:

in the specific implementation mode of the scheme 2, the half-mirror is replaced by a front surface reflector (33), and the half-mirror moves for a certain distance and rotates for a certain angle in the axial lead direction of the effective measuring beam, so that the effective reference beam and the effective measuring beam are directly combined and interfered on an interference result detector (24), and after a chassis is redesigned and installed, the installation and adjustment mode of the scheme 2 is adopted. The semi-transparent semi-reflecting mirror can be replaced by two independent front surface reflecting mirrors to respectively carry out secondary turning on the effective reference beam and the effective measuring beam, the turning vector does not have the traveling wave direction of the effective measuring beam, and the turning angle of the effective measuring beam needs to be 90 degrees so as to simplify the difficulty of post data processing, the same purpose can be realized, and the 2-time turning has the advantages of avoiding unequal chromatic dispersion, wavefront distortion and additional harmful interference results caused by the semi-reflecting mirror. Preferably, the interference result detector (24) using 2-turn should use an array color image sensor.

In the embodiments of the three embodiments, the same kind of functional devices can be exchanged between different embodiments, and the materials and the adjustment methods that are not described in the embodiments can be implemented according to the methods and materials described in the common general knowledge and the summary of the invention, and are not limited to the materials and the implementation methods in the implementation. For example, a light path adjusted by a laser is more suitable for being changed into sunlight, starlight and spontaneous radiation light as light sources for occasions with high reliability measurement, and the problems of range crossing and the like when the laser is used can be avoided; the problems of the method, such as the uncertainty of the analytic result, 8230and 8230, caused by the optical diffraction angle and the complex optical path, can be avoided by using a very simple system structure consisting of two lasers with the same frequency or locked frequency difference, and the like, are difficult to judge how to optimally realize the method under the condition of not carrying out a large amount of practices and applications. Therefore, the researchers in the industry do not need to take the specific implementation mode of the inventor as the only way to realize the content of the invention, and the researchers in the industry should select a proper mode to realize the research according to the latest achievements of the related industries and the own technical characteristics and resource advantages on the basis of not infringing the related rights of the inventor.

Claims (9)

1. A wave front division type one-way orthogonal light path interferometer device based on a 2D structure design is characterized in that parallel light with a wave front being a plane wave is used as a light source, the wave front is divided to enter a reference beam channel and a measuring beam channel respectively, light beams of the reference beam channel pass through a light delayer (11) and then enter an effective reference beam working area, light beams of the measuring beam channel pass through a 90-degree light path turning device (12) and then enter an effective measuring working area, the axial leads (17 and 18) of the two light beams entering the effective area are enabled to be orthogonal to a reflecting film layer of a half-reflecting mirror (13) to carry out beam combination through adjusting the positions and the postures of the light delayer (11) and the light path turning device (12), angles (theta 12 and theta 13) between the two light beams and the reflecting film layer are enabled to be 45 degrees, meanwhile, the axial lead length Lr of the light beams of the effective reference beam working area to be equal to the axial lead the length Lr of the two light beams to be equal to the axial leads of the effective measuring working area and the axial leads the interference light beams to be equal to the axial lead to the interference result of the half-reflecting film layer of the effective measuring working area through adjusting the light delay device, and the phase difference of the half-reflecting beam detector (14) is obtained.

2. A wave front division type one-way orthogonal light path interferometer device based on a 3D structure design is characterized in that parallel light with a wave front being a plane wave is used as a light source, the wave front is divided to enter a reference beam channel and a measuring beam channel respectively, light beams of the reference beam channel enter an effective reference beam working area after passing through a 90-degree light path turning device (21), light beams of the measuring beam channel enter an effective measuring working area after passing through a 90-degree light path turning device (22), the axial leads (27 and 28) of the two light beams entering the effective area are enabled to be orthogonal to a reflecting film layer of a half-mirror (23) to be combined through adjusting the positions and postures of the light path turning devices (21 and 22), angles (theta 21 and theta 22) between the two light beams and the surface of the reflecting film layer are enabled to be 45 degrees, meanwhile, the beam axial lead length L21 of the effective reference beam working area is enabled to be equal to the beam axial lead length L22 of the effective measuring working area through adjusting, and the combined interference light beams are measured through an interference result detector (24) to obtain phase differences of the reference beams and the measuring beams.

3. A method for reading the initial phase difference of a device in advance based on claim 1 or claim 2, then making the phase difference of the effective reference beam and the effective measuring beam different from the initial state by filling or installing the optical anisotropic light propagation medium to be measured in the effective reference working area and the effective measuring working area, or filling the optical isotropic light propagation medium with a field material in which the interferometer is moving or vibrating directionally or the effective measuring working area is changed, and obtaining the medium anisotropy parameter, the motion or vibration parameter, the field material structure and the form by capturing the change amount of the phase difference.

4. Based on the claim 1 or the claim 2, the spectral components of the collimated light source with the wave front being the plane wave are white light, white laser, dual-frequency or multi-frequency laser, dual-color or multi-color spontaneous radiation light, and the phase shift value of the resultant frequency is solved simultaneously by detecting the displacement of the 0-level interference on the interference result detector, or the phase shift decimal part of each frequency point, so that the more stable and more accurate result and the larger range can be obtained.

5. The interference result detector according to claim 1 or claim 2 is a photodetector, and converts the phase difference signal of the reference beam and the measuring beam into an electrical signal, so as to process the sampled signal by using the conventional circuit and send the electrical signal to an electronic computer for calculation and analysis.

6. Based on claim 1 or claim 2, the interference result detector is an array image sensor, and adjusts the light receiving surface of the image sensor and the combined interference optical wavefront to an attitude that is not strictly parallel, or adjusts the wavefront of the effective reference beam to an attitude that is not strictly perpendicular to the wavefront of the effective measuring beam, so that it can obtain an interference result of 0 level or more.

7. According to the claim 1 or the claim 2, on the traveling wave light path of the secondary light beam after coherent combination by using the half-mirror, a set of auxiliary detectors are installed to measure the beam directions and the spectral components of the reference light beam and the measuring light beam as the reference signals for automatic calibration, correction of assembly errors and parameter drift.

8. Based on claim 2, the half mirror is replaced by a front surface mirror (33) and moved a certain distance and rotated a certain angle in the direction of the axis of the effective measurement beam, so that the effective reference beam and the effective measurement beam are directly combined and interfered on the interference result detector.

9. Based on the claim 1 or the claim 2, the light path bending device and the half-transparent and half-reflecting mirror are arranged on a motion mechanism which can move back and forth along the axial lead direction of the effective light beam, so that the device has the capability of measuring the spatial wavelength.

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