Phase drift eliminating device for Mach-Zehnder type optical interferometer and working method of phase drift eliminating device

Abstract

The invention discloses a Mach-Zehnder type optical interferometer phase drift elimination device and a working method thereof, and relates to the technical field of optical interferometers. The device comprises a Mach-Zehnder type main and auxiliary interferometer system and a phase drift elimination processing circuit, the main interferometer system is used for detecting to obtain a main phase difference positively correlated with a main optical path difference of two arms of a main interferometer; the auxiliary interferometer system is used for detecting to obtain an auxiliary phase difference positively correlated with an auxiliary optical path difference of two arms of an auxiliary interferometer, and the main optical path difference and the auxiliary optical path difference both comprise a difference result of an optical path of a transmission medium part of a reference arm and an optical path of a transmission medium part of a measurement arm; and the phase drift elimination processing circuit is electrically connected with the two interferometer systems respectively, so that the phase drift in the main interferometer system can be eliminated by adopting conventional modes such as an open-loop mode or a closed-loop control mode according to the main phase difference and the auxiliary phase difference, further measurement errors caused by the phase drift can be avoided, and the accuracy of a measurement result is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical interferometers, and particularly relates to a device for eliminating phase drift of a Mach-Zehnder type optical interferometer and a working method thereof. Background Art

[0002] Interferometers are often used to measure small phase differences (i.e., optical path differences). For example, common Michelson interferometers and Mach-Zehnder type interferometers can both measure small phase differences. The measurement principle of the aforementioned interferometers is as follows: By measuring the bright and dark fringes (with different light intensity variations) generated by the interference of light beams in two arms (i.e., the reference arm and the measurement arm), the optical path difference between the two arms can be accurately measured, thereby achieving the purpose of accurately measuring the optical path. Through small changes in the optical path, small changes in physical quantities such as distance or refractive index can be accurately measured. For example, in the application of distance measurement, light with a wavelength of about the micron order is generally used. If a change in wavelength of one-thousandth can be measured, an accurate measurement purpose at the nanometer order or even sub-nanometer order can be achieved.

[0003] As Figure 1 shown, the prior art provides a Mach-Zehnder type interferometer for distance measurement, which is equipped with a circulator (as Figure 1 shown, it has the following working characteristics: Light incident from the P1 end can only be transmitted to the P2 end and cannot be transmitted to the P3 end; light incident from the P2 end can only be transmitted to the P3 end and cannot be transmitted to the P1 end; and light incident from the P3 end will be blocked) and a collimator, and can be applied to distance measurement in many lidars (especially lidars based on the frequency modulation continuous wave method). As Figure 2 shown, the prior art also provides another Mach-Zehnder type interferometer for distance measurement (which is a variant of Figure 1 ). In this optical configuration, the collimated emission and reception of light do not use the same set of collimation systems, and the aperture of the receiving collimator is often made larger to facilitate the reception of reflected light signals.

[0004] Although the construction of the above-mentioned Mach-Zehnder type interferometer is simple, there is an inherent defect: Although the spatial optical path part of the two arms of the interferometer is often used to measure actual physical quantities and its refractive index is less affected by the environment, the medium parts of the two arms of the interferometer (i.e., the two-arm optical fibers and phase modulators, etc.) are easily affected by the environment and change the refractive index, resulting in a drift of the optical path of the two arms, that is, the interferometer undergoes phase drift, which will lead to a large measurement error. Therefore, the measurement error cannot reach the wavelength order (generally the micron order) and smaller orders. In order to make the measurement accuracy better than the micron order, some means must be adopted to eliminate the measurement error caused by phase drift. Summary of the Invention

[0005] The object of the present invention is to provide a device for eliminating phase drift of a Mach-Zehnder interferometer and its working method, so as to solve the problem that the existing Mach-Zehnder interferometer has limited measurement accuracy due to phase drift.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, a device for eliminating phase drift of a Mach-Zehnder interferometer is provided, which includes a Mach-Zehnder main interferometer system, a Mach-Zehnder auxiliary interferometer system, and a phase drift elimination processing circuit;

[0008] The Mach-Zehnder main interferometer system is used to detect a main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer. The two arms of the main interferometer include a main interferometer reference arm and a main interferometer measurement arm. The main optical path difference between the two arms of the main interferometer refers to the difference result between the optical path of the main interferometer measurement arm and the optical path of the main interferometer reference arm. The optical path of the main interferometer measurement arm includes a partial optical path of the main measurement arm transmission medium and a partial optical path of the main measurement arm spatial optical path;

[0009] The Mach-Zehnder auxiliary interferometer system is used to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. The two arms of the auxiliary interferometer include an auxiliary interferometer reference arm and an auxiliary interferometer measurement arm. The auxiliary optical path difference between the two arms of the auxiliary interferometer refers to the difference result between the optical path of the auxiliary interferometer measurement arm and the optical path of the auxiliary interferometer reference arm. The optical path of the auxiliary interferometer reference arm overlaps with the optical path of the main interferometer reference arm. The optical path of the auxiliary interferometer measurement arm includes a partial optical path of the auxiliary measurement arm transmission medium and a partial optical path of the auxiliary measurement arm spatial optical path;

[0010] The partial optical path of the main measurement arm transmission medium overlaps with the partial optical path of the auxiliary measurement arm transmission medium. The partial optical path of the main measurement arm spatial optical path includes a first spatial optical path part that completely overlaps with the partial optical path of the auxiliary measurement arm spatial optical path and a second spatial optical path part that does not overlap with the partial optical path of the auxiliary measurement arm spatial optical path. The demarcation point between the first spatial optical path part and the second spatial optical path part is at any position in the partial optical path of the main measurement arm spatial optical path;

[0011] The input end of the phase drift elimination processing circuit is electrically connected to the main phase difference detection result output end of the Mach-Zehnder main interferometer system and the auxiliary phase difference detection result output end of the Mach-Zehnder auxiliary interferometer system respectively.

[0012] Based on the above invention content, a new scheme for eliminating the phase drift of a Mach-Zehnder type main optical interferometer by using a Mach-Zehnder type auxiliary interferometer is provided, which includes a Mach-Zehnder type main interferometer system, a Mach-Zehnder type auxiliary interferometer system, and a phase drift elimination processing circuit. Among them, the Mach-Zehnder type main interferometer system is used to detect a main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer. The Mach-Zehnder type auxiliary interferometer system is used to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. Both the main optical path difference and the auxiliary optical path difference include the phase difference result between the partial optical path of the reference arm transmission medium and the partial optical path of the measurement arm transmission medium. The phase drift elimination processing circuit is electrically connected to the two interferometer systems respectively. In this way, according to the main phase difference and the auxiliary phase difference, conventional methods such as open-loop mode or closed-loop control mode can be used to eliminate the phase drift in the main interferometer system, thereby avoiding measurement errors caused by phase drift, ensuring the accuracy of measurement results, and facilitating practical application and popularization.

[0013] In a possible design, the control signal output terminal of the phase drift elimination processing circuit is also electrically connected to the controlled terminals of the adjustable components of the partial optical path of the transmission medium and / or the adjustable components of the partial optical path of the spatial optical path in the two arms of the main interferometer. Among them, the adjustable component of the partial optical path of the transmission medium is used to change the partial optical path of the main reference arm transmission medium and / or the partial optical path of the main measurement arm transmission medium, and the adjustable component of the partial optical path of the spatial optical path is used to change the partial optical path of the first spatial optical path.

[0014] In a second aspect, a working method of the Mach-Zehnder type optical interferometer phase drift elimination device as described in the possible design of the first aspect is provided, which is executed by the phase drift elimination processing circuit and includes:

[0015] According to the auxiliary phase difference detection result from the Mach-Zehnder type auxiliary interferometer system, control the adjustable components of the partial optical path of the transmission medium and / or the adjustable components of the partial optical path of the spatial optical path in the two arms of the main interferometer to change the optical path, so that the phase drift of the Mach-Zehnder type auxiliary interferometer system is always at zero or a certain fixed phase, so as to lock the phase drift of the Mach-Zehnder type main interferometer system at zero or a certain fixed phase.

[0016] In a third aspect, another working method of the Mach-Zehnder type optical interferometer phase drift elimination device as described in the first aspect is provided, which is executed by the phase drift elimination processing circuit and includes:

[0017] The main optical path difference is obtained by converting the main phase difference of the Mach-Zehnder type main interferometer system, and the auxiliary optical path difference is obtained by converting the auxiliary phase difference of the Mach-Zehnder type auxiliary interferometer system. Then, the main optical path difference is subtracted from the auxiliary optical path difference to eliminate the inherent phase drift of the Mach-Zehnder type main interferometer, and the actual measurement value is obtained.

[0018] Advantages of the above solution:

[0019] (1) The present invention creatively provides a new solution for eliminating the phase drift of a Mach-Zehnder type main optical interferometer by using a Mach-Zehnder type auxiliary interferometer, that is, it includes a Mach-Zehnder type main interferometer system, a Mach-Zehnder type auxiliary interferometer system, and a phase drift elimination processing circuit. Among them, the Mach-Zehnder type main interferometer system is used to detect the main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer, and the Mach-Zehnder type auxiliary interferometer system is used to detect the auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. Both the main optical path difference and the auxiliary optical path difference include the phase difference result of the partial optical path of the reference arm transmission medium and the partial optical path of the measurement arm transmission medium. The phase drift elimination processing circuit is electrically connected to the two interferometer systems respectively. In this way, according to the main phase difference and the auxiliary phase difference, the phase drift in the main interferometer system can be eliminated by using conventional methods such as open-loop or closed-loop control methods, thereby avoiding measurement errors caused by phase drift, ensuring the accuracy of the measurement results, and facilitating practical application and promotion.

[0020] (2) It can also reduce the influence caused by return loss to the lowest level, further ensuring the accuracy of the measurement results. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a schematic diagram of the ranging application structure of a Mach-Zehnder type interferometer in the prior art.

[0023] Figure 2 It is a schematic diagram of the ranging application structure of another Mach-Zehnder type interferometer in the prior art.

[0024] Figure 3 It is a schematic diagram of the structure of the first Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiment of the present application, where Figure 3(a) shows a schematic diagram of the complete structure of the first Mach-Zehnder type optical interferometer phase drift elimination device. Figure 3 (b) shows a schematic diagram of the structure of the Mach-Zehnder type main interferometer system in the first Mach-Zehnder type optical interferometer phase drift elimination device. Figure 3 (c) shows a schematic diagram of the structure of the Mach-Zehnder type auxiliary interferometer system in the first Mach-Zehnder type optical interferometer phase drift elimination device.

[0025] Figure 4 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the second Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0026] Figure 5 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the third Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0027] Figure 6 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the fourth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0028] Figure 7 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the fifth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0029] Figure 8 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the sixth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0030] Figure 9 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the seventh Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0031] Figure 10 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the eighth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0032] Figure 11 This is a schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the ninth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0033] Figure 12Schematic diagram of the combined structure of the main interference system and the auxiliary interference system in the tenth Mach-Zehnder type optical interferometer phase drift elimination device provided by the embodiments of the present application.

[0034] In the above-mentioned drawings: 1 - circulator; 11 - first spatial circulator; 110 - first circulator; 12 - second spatial circulator; 120 - second circulator; 2 - collimator; 201 - first emission collimator; 202 - second emission collimator; 211 - first receiving collimator; 212 - second receiving collimator; 3 - dichroic mirror; 301 - first dichroic mirror; 302 - second dichroic mirror; 303 - third dichroic mirror; 51 - first Y-branch phase modulator; 51 - second Y-branch phase modulator; 61 - first filter; 62 - second filter; 7 - optical coupler; 100 - object under test; 200 - reference mirror. Detailed implementation manners

[0035] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the embodiments of the present application in combination with the drawings and the descriptions of the embodiments or the prior art. Obviously, the following descriptions of the structures of the drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained according to the descriptions of these embodiments. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but do not constitute a limitation to the present invention.

[0036] It should be understood that although terms such as first and second etc. may be used herein to describe various objects, these objects should not be limited by these terms. These terms are only used to distinguish one object from another. For example, the first object can be called the second object, and similarly, the second object can be called the first object, without departing from the scope of the exemplary embodiments of the present application.

[0037] It should be understood that for the term "and / or" that may appear herein, it is only a description of the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, B exists alone, or A and B exist simultaneously, etc.; another example, A, B and / or C can represent any one of A, B and C or any combination of them; for the term "or and" that may appear herein, it is a description of another association object relationship, indicating that two relationships can exist. For example, A or and B can represent: A exists alone or A and B exist simultaneously, etc.; in addition, for the character " / " that may appear herein, generally it represents that the front and rear associated objects are in an "or" relationship.

[0038] Embodiment 1

[0039] As Figure 3 shown, the first Mach-Zehnder type optical interferometer phase drift elimination device provided in this embodiment includes, but is not limited to, a Mach-Zehnder type main interferometer system, a Mach-Zehnder type auxiliary interferometer system, and a phase drift elimination processing circuit; the Mach-Zehnder type main interferometer system is used to detect a main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer. The two arms of the main interferometer include a main interferometer reference arm and a main interferometer measurement arm. The main optical path difference between the two arms of the main interferometer refers to the difference between the optical path of the main interferometer measurement arm and the optical path Lab of the main interferometer reference arm. The optical path of the main interferometer measurement arm includes a partial optical path La2 of the transmission medium of the main measurement arm and a partial optical path Lb2 of the spatial optical path of the main measurement arm.

[0040] As Figure 3 (b) shown, the Mach-Zehnder type main interferometer system can, but is not limited to, adopt an existing Mach-Zehnder type fiber optic interferometer. Specifically, the partial optical path of the transmission medium of the main measurement arm includes the partial optical path of the transmission medium from the optical coupling region on the incident light side of the two arms of the main interferometer (i.e., Figure 3 the fiber optic coupler 1 shown in Figure 3 ) to the first port of the circulator 1 (i.e., Figure 3 P1 shown in Figure 3 ), the partial optical path of the transmission medium from the first port of the circulator 1 to the second port of the circulator 1 (i.e., Figure 3 P2 shown in Figure 3As shown, a phase modulator is configured in a partial optical path of the transmission medium for open-loop or closed-loop phase drift cancellation). The optical principle by which the Mach-Zehnder type main interferometer system detects the main phase difference is a prior art. Assuming that the wavelength of the light emitted by the light source 1 is λ1, the detector 1 can be converted based on the working principle of the existing Mach-Zehnder type interferometer to obtain an electrical signal for reflecting the main phase difference as In addition, the Mach-Zehnder type main interferometer system can also be specifically implemented by using an existing optical waveguide type Mach-Zehnder type interferometer or other forms of Mach-Zehnder type interferometers.

[0041] The Mach-Zehnder type auxiliary interferometer system is used to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. The two arms of the auxiliary interferometer include an auxiliary interferometer reference arm and an auxiliary interferometer measurement arm. The auxiliary optical path difference between the two arms of the auxiliary interferometer refers to the difference result between the optical path of the auxiliary interferometer measurement arm and the optical path of the auxiliary interferometer reference arm. The optical path of the auxiliary interferometer reference arm overlaps with the optical path of the main interferometer reference arm (as Figure 3 shown, in this embodiment, it is a complete overlap). The optical path of the auxiliary interferometer measurement arm includes a partial optical path of the transmission medium of the auxiliary measurement arm and a partial optical path of the spatial optical path of the auxiliary measurement arm. The partial optical path of the transmission medium of the main measurement arm overlaps with the partial optical path of the transmission medium of the auxiliary measurement arm. The partial optical path of the spatial optical path of the main measurement arm includes a first spatial optical path portion Lb21 that completely overlaps with the partial optical path of the spatial optical path of the auxiliary measurement arm and a second spatial optical path portion that does not overlap with the partial optical path of the spatial optical path of the auxiliary measurement arm. The demarcation point between the first spatial optical path portion and the second spatial optical path portion is at an arbitrary position in the partial optical path of the spatial optical path of the main measurement arm.

[0042] As Figure 3 (c) shown, the Mach-Zehnder type auxiliary interferometer system can also but is not limited to using an existing Mach-Zehnder type fiber optic interferometer. Specifically, the partial optical path of the transmission medium of the auxiliary measurement arm includes a partial optical path of the transmission medium from the light coupling region on the light input side of the two arms of the auxiliary interferometer (i.e., Figure 3 the fiber optic coupler 1 shown in Figure 3The optical path of the transmission medium part of the fiber optic coupler 2) shown in the figure. The optical path of the spatial optical path part of the auxiliary measurement arm only includes the first spatial optical path part, that is, only includes the spatial optical path part from the collimator 2 to the dichroic mirror 3 and the spatial optical path part from the dichroic mirror 3 to the collimator 2 (at this time, the second spatial optical path part includes the spatial optical path part from the dichroic mirror 3 to the object under test 100 and the spatial optical path part from the object under test 100 to the dichroic mirror 3; the demarcation point between the first spatial optical path part and the second spatial optical path part is the position where the dichroic mirror 3 is located). Among them, the dichroic mirror 3 is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect back the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system. The light emitted by the main light source is the light emitted by the light source 1 in Figure 3 (it can be monochromatic light, or two or more different wavelengths of light, or light with a certain spectral width, that is, white light interference). The light emitted by the auxiliary light source is the light emitted by the light source 2 in Figure 3 (it can also be monochromatic light, or two or more different wavelengths of light, or light with a certain spectral width, that is, white light interference). The light emitted by the main light source and the light emitted by the auxiliary light source are lights with different wavelengths (that is, the wavelengths of the two lights are different) and are combined by the wavelength division multiplexer WDM1 shown in Figure 3 and input into the common light input side optical coupling area of the two arms of the main interferometer and the two arms of the auxiliary interferometer (that is, the fiber optic coupler 1 shown in Figure 3 ). In addition, the main interference light of the Mach-Zehnder type main interferometer system and the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system are also split by the wavelength division multiplexer WDM2 shown in Figure 3 and then respectively input into the main detector of the Mach-Zehnder type main interferometer system (that is, the detector 1 shown in Figure 3 ) and the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system (that is, the detector 2 shown in Figure 3 ).

[0043] As shown in Figure 3 (c), the optical principle of the Mach-Zehnder type auxiliary interferometer system for detecting the auxiliary phase difference can also be obtained conventionally with reference to the prior art. Let the wavelength of the light emitted by the auxiliary light source be λ2, then the detector 2 can be converted based on the working principle of the existing Mach-Zehnder type interferometer to obtain an electrical signal for reflecting the auxiliary phase difference as . In addition, Figure 3 The wavelength division multiplexer WDM1 and the wavelength division multiplexer WDM1 shown in the figure can also be replaced with other components such as couplers.

[0044] The input end of the phase drift cancellation processing circuit is electrically connected to the main phase difference detection result output end of the Mach-Zehnder main interferometer system and the auxiliary phase difference detection result output end of the Mach-Zehnder auxiliary interferometer system respectively. As Figure 3 shown, specifically, the electrical signal output end of the detector 1 is used as the main phase difference detection result output end of the Mach-Zehnder main interferometer system and is electrically connected to the input end of the phase drift cancellation processing circuit, and the electrical signal output end of the detector 2 is used as the auxiliary phase difference detection result output end of the auxiliary interferometer system and is also electrically connected to the input end of the phase drift cancellation processing circuit. The control signal output end of the phase drift cancellation processing circuit is also electrically connected to the controlled ends of the optical path adjustable components in the transmission medium part and / or the spatial optical path part of the two arms of the main interferometer. In this way, high-frequency and periodic phase modulation signals can be loaded on the two arms of the Mach-Zehnder main interferometer system and the Mach-Zehnder auxiliary interferometer system at the same time, so that the optical signals reaching the detector 1 and the detector 2 respectively also show a high-frequency periodic oscillation phenomenon. Furthermore, according to the high-frequency periodic signals received by the detectors, methods such as lock-in amplification, phase discrimination, and spectrum analysis can be used to demodulate the main phase difference and the auxiliary phase difference, and finally a very high demodulation accuracy can be achieved. For example, for light waves with a wavelength in the micron order of magnitude, the optical path difference corresponding to the demodulated phase difference can reach the nanometer order of magnitude, or even the sub-nanometer order of magnitude.

[0045] The phase drift cancellation processing circuit eliminates the phase drift in the Mach-Zehnder main interferometer system by using conventional methods such as open-loop mode or closed-loop control mode according to the phase difference Δφ1 and the auxiliary phase difference Δφ fz,1 , that is, since the optical path of the reference arm of the auxiliary interferometer overlaps with the optical path of the reference arm of the main interferometer (completely overlaps in this embodiment), the optical path of the transmission medium part of the main measurement arm overlaps with the optical path of the transmission medium part of the auxiliary measurement arm. In this way, even if the refractive index and length of the transmission medium part of the reference arm and / or the measurement arm are easily affected by the external environment and the optical path changes, this optical path change will affect both the Mach-Zehnder main interferometer system and the Mach-Zehnder auxiliary interferometer system at the same time, and the affected values are the same. Therefore, the phase drift cancellation processing circuit can use the phase drift of the Mach-Zehnder auxiliary interferometer system to cancel the phase drift of the Mach-Zehnder main interferometer system. For example, the following open-loop mode is adopted: the main optical path difference La2+Lb2-Lab is conventionally calculated according to the main phase difference Δφ1 of the Mach-Zehnder main interferometer system, and according to the auxiliary phase difference Δφ of the Mach-Zehnder auxiliary interferometer system fz,1The auxiliary optical path difference La2+Lb21-Lab is obtained by conventional conversion, and then the main optical path difference is subtracted from the auxiliary optical path difference, so that the inherent phase drift of the Mach-Zehnder type main interferometer can be eliminated, and the actual measurement value can be obtained. In addition, specifically, the phase drift elimination processing circuit can be implemented by, but not limited to, conventional means such as existing microprocessor chips, single-chip microcomputer chips or logic programmable devices; and in practical applications, the object to be measured on the measurement arm can also be replaced with a mirror, and a light-transmitting solid medium or a light-transmitting container filled with a fluid medium can be placed in front of the mirror. At this time, a slight change in the refractive index of the medium can also cause a change in the optical path, so that the device can measure a slight change in the refractive index of the medium.

[0046] Preferably, in order to enable the phase drift elimination processing circuit to conventionally eliminate the phase drift in the Mach-Zehnder type main interferometer system through a closed-loop control method, the control signal output end of the phase drift elimination processing circuit can not only load a high-frequency and periodic phase modulation signal for phase demodulation on the controlled ends of the optical path adjustable components in the transmission medium part and / or the spatial optical path part of the two arms of the Michelson interferometer, but also load a feedback signal at the same time. Among them, the optical path adjustable component in the transmission medium part is used to change the optical path of the transmission medium part of the main reference arm and / or the optical path of the transmission medium part of the main measurement arm, and the optical path adjustable component in the spatial optical path part is used to change the optical path of the first spatial optical path part. The optical path adjustable component in the transmission medium part includes, but is not limited to, a phase modulator, a fiber stretching phase modulator, a temperature-controlled phase modulator and / or a Y-branch phase modulator, etc.; as Figure 3 shown, the optical path adjustable component in the transmission medium part can be, for example but not limited to, the phase modulator; the optical path adjustable component in the spatial optical path part can be, for example but not limited to, a mechanical moving component used to change the position of the demarcation point between the optical path of the transmission medium part of the main measurement arm and the optical path of the spatial optical path part of the main measurement arm. Among them, the mechanical moving component can be implemented by, but not limited to, a conventional moving mechanical structure based on a PZT (Piezoelectric Ceramic Transducer) piezoelectric ceramic driver and / or a slide rail, etc.; in addition, the optical path adjustable component in the spatial optical path part can also be implemented by using an existing spatial phase modulator. In addition, the mechanical moving component can also be used to change the position of the dichroic mirror 3 (that is, change the demarcation point between the optical path of the first spatial optical path part and the optical path of the second spatial optical path part).

[0047] Further preferably, the working method of the Mach-Zehnder optical interferometer phase drift elimination device is executed by a phase drift elimination processing circuit, including but not limited to: according to the auxiliary phase difference detection result from the Mach-Zehnder auxiliary interferometer system, controlling the optical path adjustable components in the transmission medium part of the two arms of the main interferometer and / or the optical path adjustable components in the spatial optical path part to change the optical path, so that the phase drift of the Mach-Zehnder auxiliary interferometer system is always at zero or a certain fixed phase, so as to lock the phase drift of the Mach-Zehnder main interferometer system at zero or a certain fixed phase.

[0048] Preferably, when the demarcation point between the first spatial optical path part optical path and the second spatial optical path part optical path is the collimator 2 or the fiber end face corresponding to the collimator 2, the dichroic mirror 3 is realized by coating a dichroic film on the collimator 2 or the fiber end face. At this time, Lb21 = 0, that is, there is no optical path of the auxiliary measurement arm spatial optical path part and the first spatial optical path part optical path (and at this time, it is also impossible to change this optical path through the optical path adjustable component of the spatial optical path part).

[0049] Preferably, the two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light input side optical coupling area, wherein the light input side optical coupling area has at least one additional first optical transmission channel; the light emitted by the main light source of the Mach-Zehnder main interferometer system is input into the light input side optical coupling area through any one of the at least one first optical transmission channels, so that the light emitted by the main light source is respectively coupled to the two arms of the main interferometer; the light emitted by the auxiliary light source of the Mach-Zehnder auxiliary interferometer system is input into the light input side optical coupling area through any one of the at least one first optical transmission channels, so that the light emitted by the auxiliary light source is respectively coupled to the two arms of the auxiliary interferometer. As Figure 3 shown, the light input side optical coupling area is the fiber coupler 1, and there are also two additional first optical transmission channels on its left; the light emitted by the main light source of the Mach-Zehnder main interferometer system and the light emitted by the auxiliary light source of the Mach-Zehnder auxiliary interferometer system are input into the light input side optical coupling area through one of the first optical transmission channels. At this time, a wavelength division multiplexer or a dichroic device needs to be arranged in this first optical transmission channel to combine the light emitted by the main light source and the light emitted by the auxiliary light source. In addition, various optical fiber components such as couplers, isolators, circulators, wavelength division multiplexers, filters, and / or attenuators can be arranged in the first optical transmission channel as needed but not limited to this.

[0050] Preferably, the two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light output-side optical coupling region, where the light output-side optical coupling region has at least one additional second optical transmission channel; the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through any one of the at least one second optical transmission channels, or when the at least one second optical transmission channel includes two second optical transmission channels with output optical signal phases being opposite to each other, the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through the two second optical transmission channels (at this time, the number of main detectors can be two and is connected to the two second optical transmission channels in one-to-one correspondence), so as to use the main detector to detect the main phase difference that is positively correlated with the optical path difference between the two arms of the main interferometer, where the main interference light refers to the interference result of the light that converges after passing through the two arms of the main interferometer and all comes from the main light source of the Mach-Zehnder type main interferometer system in the light output-side optical coupling region; the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through any one of the at least one second optical transmission channels, or when the at least one second optical transmission channel includes two second optical transmission channels with output optical signal phases being opposite to each other, the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through the two second optical transmission channels (referring to the main detector, at this time, the number of auxiliary detectors can also be two and is connected to the two second optical transmission channels in one-to-one correspondence), so as to use the auxiliary detector to detect the auxiliary phase difference that is positively correlated with the auxiliary optical path difference, where the auxiliary interference light refers to the interference result of the light that converges after passing through the two arms of the auxiliary interferometer and all comes from the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system in the light output-side optical coupling region. As Figure 3 shown, the light output-side optical coupling region is the fiber coupler 2, and there are also two additional second optical transmission channels on its right side; the light emitted by the main light source of the Mach-Zehnder type main interferometer system and the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system are output from the light input-side optical coupling region through one of the second optical transmission channels. At this time, a wavelength division multiplexer or a dichroic device, etc. needs to be arranged in this second optical transmission channel to split the light emitted by the main light source and the light emitted by the auxiliary light source. In addition, various fiber components such as couplers, isolators, circulators, wavelength division multiplexers, filters, and / or attenuators can also be arranged in the second optical transmission channel as needed but not limited to this.

[0051] In addition, in all the above spatial optical paths, optical elements such as focusing objective lenses, beam expanders, various transmission lenses, and / or reflecting mirrors can be installed as needed to achieve the purpose of this embodiment.

[0052] In summary, by adopting the first Mach-Zehnder type optical interference phase drift elimination device and its working method provided in this embodiment, the following technical effects are achieved:

[0053] (1) This embodiment provides a new solution for eliminating the phase drift of the Mach-Zehnder type main optical interferometer by using a Mach-Zehnder type auxiliary interferometer, that is, it includes a Mach-Zehnder type main interferometer system, a Mach-Zehnder type auxiliary interferometer system, and a phase drift elimination processing circuit. Among them, the Mach-Zehnder type main interferometer system is used to detect the main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer, and the Mach-Zehnder type auxiliary interferometer system is used to detect the auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. Both the main optical path difference and the auxiliary optical path difference include the phase difference results of the partial optical paths of the reference arm transmission medium and the measurement arm transmission medium. The phase drift elimination processing circuit is electrically connected to the two interferometer systems respectively. In this way, according to the main phase difference and the auxiliary phase difference, conventional methods such as open-loop or closed-loop control methods can be used to eliminate the phase drift in the main interferometer system, thereby avoiding measurement errors caused by phase drift, ensuring the accuracy of measurement results, and facilitating practical application and popularization.

[0054] Embodiment 2

[0055] As Figure 4As shown, on the basis of the technical solution of Embodiment 1, this embodiment further provides the second Mach-Zehnder interferometer phase drift elimination device. The difference from Embodiment 1 is that: the optical path of the transmission medium in the main measurement arm includes the optical path of the transmission medium from the light coupling regions on the light incident sides of the two arms of the main interferometer to the first emission collimator 201 and the optical path of the transmission medium from the first receiving collimator 211 to the light coupling regions on the light output sides of the two arms of the main interferometer. The optical path of the spatial optical path in the main measurement arm includes the optical path of the spatial optical path from the first emission collimator 201 to the first port of the first spatial circulator 11, the optical path of the spatial optical path from the first port of the first spatial circulator 11 to the second port of the first spatial circulator 11, the optical path of the spatial optical path from the second port of the first spatial circulator 11 to the measured object 100, the optical path of the spatial optical path from the measured object 100 to the second port of the first spatial circulator 11, the optical path of the spatial optical path from the second port of the first spatial circulator 11 to the third port of the first spatial circulator 11, and the optical path of the spatial optical path from the third port of the first spatial circulator 11 to the first receiving collimator 211. The first optical path of the spatial optical path includes the optical path of the spatial optical path from the first emission collimator 201 to the first port of the first spatial circulator 11, the optical path of the spatial optical path from the first port of the first spatial circulator 11 to the second port of the first spatial circulator 11, the optical path of the spatial optical path from the second port of the first spatial circulator 11 to the dichroic mirror 3, the optical path of the spatial optical path from the dichroic mirror 3 to the second port of the first spatial circulator 11, the optical path of the spatial optical path from the second port of the first spatial circulator 11 to the third port of the first spatial circulator 11, and the optical path of the spatial optical path from the third port of the first spatial circulator 11 to the first receiving collimator 211. The second optical path of the spatial optical path includes the optical path of the spatial optical path from the dichroic mirror 3 to the measured object 100 and the optical path of the spatial optical path from the measured object 100 to the dichroic mirror 3. Among them, the first port of the first spatial circulator 11 is used to transmit the incident light only to the second port of the first spatial circulator 11 and emit it. The second port of the first spatial circulator 11 is used to transmit the incident light only to the third port of the first spatial circulator 11 and emit it. The dichroic mirror 3 is used to allow the light emitted by the main light source of the Mach-Zehnder main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder auxiliary interferometer system back.

[0056] As Figure 4As shown in the figure, the main differences between this embodiment and the first embodiment are as follows: the first spatial circulator 11 located in the optical path of the spatial optical path part of the measuring arm replaces the circulator 1 located in the optical path of the transmission medium part of the measuring arm, and the first transmitting collimator 201 and the first receiving collimator 211 are also used to replace the collimator 2 with the characteristics of integrated transceiver, and the mechanical moving parts are respectively configured for the first transmitting collimator 201 and the first receiving collimator 211. Thus, considering the existence of return loss, by replacing the fiber optic circulator (i.e., the circulator 1) with a spatial circulator (i.e., the first spatial circulator 11), it is possible to eliminate Figure 3 the influence of the return loss of the medium optical path between the circulator 1 and the collimator 2 (in the first embodiment, the return loss parameters of the optical devices in this optical path need to be strictly controlled), that is, the influence caused by the return loss can be reduced to the lowest, further ensuring the accuracy of the measurement result.

[0057] Based on the technical effects of the foregoing first embodiment, the technical effects of this embodiment further include: (1) the influence caused by the return loss can be reduced to the lowest, further ensuring the accuracy of the measurement result.

[0058] Embodiment Three

[0059] As Figure 5As shown in the figure, on the basis of the technical solution of the second embodiment, the present embodiment further provides the third Mach-Zehnder type optical interferometer phase drift elimination device, which is different from the second embodiment in that: the optical path of the transmission medium in the main measurement arm includes the optical path of the transmission medium from the light coupling area on the light incident side of the two arms of the main interferometer to the first emission collimator 201 and the optical path of the transmission medium from the first receiving collimator 211 to the light coupling area on the light output side of the two arms of the main interferometer; the optical path of the spatial optical path in the main measurement arm includes the optical path of the spatial optical path from the first emission collimator 201 to the object to be measured 100 and the optical path of the spatial optical path from the object to be measured 100 to the first receiving collimator 211; the first spatial optical path includes the optical path of the spatial optical path from the first emission collimator 201 to the first dichroic mirror 301 and the optical path of the spatial optical path from the second dichroic mirror 302 to the first receiving collimator 211; the second spatial optical path includes the optical path of the spatial optical path from the first dichroic mirror 301 to the object to be measured 100 and the optical path of the spatial optical path from the object to be measured 100 to the second dichroic mirror 302; the optical path of the spatial optical path in the auxiliary measurement arm includes the first spatial optical path and the known optical path of the spatial optical path from the first dichroic mirror 301 to the second dichroic mirror 302 that does not overlap with the optical path of the spatial optical path in the main measurement arm. Among them, the first dichroic mirror 301 is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system to the second dichroic mirror 302, and the second dichroic mirror 302 is used to allow the light emitted by the main light source to pass through and reflect the light emitted by the auxiliary light source to the first receiving collimator 211.

[0060] As Figure 5 shown in the figure, the main difference between this embodiment and the second embodiment is that: in the optical path of the spatial optical path in the measurement arm, the first spatial type circulator 11 is replaced by a dichroic structure composed of the first dichroic mirror 301 and the second dichroic mirror 302, so that the light emitted by the auxiliary light source can be directly transmitted from the first emission collimator 201 to the first receiving collimator 211. Although the optical path of the spatial optical path in the auxiliary measurement arm also includes the optical path of the spatial optical path from the first dichroic mirror 301 to the second dichroic mirror 302 that does not overlap with the optical path of the spatial optical path in the main measurement arm, since this optical path of the spatial optical path is known (default to have stability), the first spatial optical path can still be accurately obtained conventionally based on this known optical path, thereby achieving the purpose of eliminating phase drift, and the influence caused by return loss can also be reduced to the lowest level, further ensuring the accuracy of the measurement result. In addition, the dichroic structure can adopt Figure 5The form in which the two dichroic mirrors shown are placed at a 45° tilt can also adopt other different forms.

[0061] The technical details and technical effects of this embodiment can be derived by referring to the aforementioned second embodiment, and will not be elaborated here.

[0062] Embodiment Four

[0063] As Figure 6 shown, on the basis of the technical solution of the second embodiment, this embodiment further provides the fourth Mach-Zehnder type optical interferometer phase drift elimination device. The difference from the second embodiment is that: the optical path of the reference arm of the main interferometer includes the optical path of the transmission medium part from the light coupling regions on the light incident sides of the two arms of the main interferometer to the second emission collimator 202, the optical path of the spatial optical path part from the second emission collimator 202 to the second reception collimator 212, and the optical path of the transmission medium part from the second reception collimator 212 to the light coupling regions on the light output sides of the two arms of the main interferometer. At this time, the optical path of the reference arm of the auxiliary interferometer includes the optical path of the transmission medium part from the light coupling regions on the light incident sides of the two arms of the auxiliary interferometer to the second emission collimator 202, the optical path of the spatial optical path part from the second emission collimator 202 to the second reception collimator 212, and the optical path of the transmission medium part from the second reception collimator 212 to the light coupling regions on the light output sides of the two arms of the auxiliary interferometer, and still completely overlaps with the optical path of the reference arm of the auxiliary interferometer. In addition, mechanical moving parts can be respectively configured for the second emission collimator 202 and the second reception collimator 212 to enrich the ways of open-loop or closed-loop control.

[0064] The technical details and technical effects of this embodiment can be derived by referring to the aforementioned second embodiment, and will not be elaborated here.

[0065] Embodiment Five

[0066] As Figure 7As shown in the figure, on the basis of the technical solution of Embodiment 4, this embodiment further provides the fifth Mach-Zehnder type optical interferometer phase drift elimination device, which is different from Embodiment 4 in that: the optical path overlap between the reference arm of the auxiliary interferometer and the reference arm of the main interferometer includes the following partial overlap cases: the optical path of the spatial optical path part from the second emission collimator 202 to the second reception collimator 212 includes the optical path of the spatial optical path part from the second emission collimator 202 to the first port of the second spatial circulator 12, the optical path of the spatial optical path part from the first port of the second spatial circulator 12 to the second port of the second spatial circulator 12, the optical path of the spatial optical path part from the second port of the second spatial circulator 12 to the third dichroic mirror 303, the optical path of the spatial optical path part from the third dichroic mirror 303 to the reference mirror 200, the optical path of the spatial optical path part from the reference mirror 200 to the third dichroic mirror 303, the optical path of the spatial optical path part from the third dichroic mirror 303 to the second port of the second spatial circulator 12, the optical path of the spatial optical path part from the second port of the second spatial circulator 12 to the third port of the second spatial circulator 12, and the optical path of the spatial optical path part from the third port of the second spatial circulator 12 to the second reception collimator 212. Among them, the optical path of the spatial optical path part from the third dichroic mirror 303 to the reference mirror 200 and the optical path of the spatial optical path part from the reference mirror 200 to the third dichroic mirror 303 are respectively the known optical paths of the spatial optical path parts that do not overlap with the optical path of the reference arm of the main interferometer. Thus, although the optical path of the reference arm of the auxiliary interferometer and the optical path of the reference arm of the main interferometer are partially overlapped, since the optical paths of the non-overlapped parts are known, the purpose of phase drift elimination can also be conventionally achieved based on these known optical paths. In addition, if the optical path of the spatial optical path part from the third dichroic mirror 303 to the reference mirror 200 and the optical path of the spatial optical path part from the reference mirror 200 to the third dichroic mirror 303 are both zero, then the optical path overlap between the reference arm of the auxiliary interferometer and the reference arm of the main interferometer is a complete overlap case; and mechanical moving parts can be respectively configured for the second emission collimator 202 and the second reception collimator 212 to enrich the ways of open-loop or closed-loop control.

[0067] The technical details and technical effects of this embodiment can be deduced by referring to the aforementioned Embodiment 4 and will not be elaborated here.

[0068] Embodiment 6

[0069] As Figure 8As shown in the figure, on the basis of the technical solution of Embodiment 2, this embodiment further provides the sixth Mach-Zehnder type optical interferometer phase drift elimination device, which is different from Embodiment 2 in that: the light input coupling area shared by the two arms of the main interferometer and the two arms of the auxiliary interferometer is realized by a first Y-shaped branch phase modulator 51. At this time, the partial optical path adjustable component of the transmission medium may include the first Y-shaped branch phase modulator 51.

[0070] The technical details and technical effects of this embodiment can be deduced by referring to the foregoing Embodiment 2, and will not be elaborated here.

[0071] Embodiment 7

[0072] As Figure 9 As shown in the figure, on the basis of the technical solution of Embodiment 6, this embodiment further provides the seventh Mach-Zehnder type optical interferometer phase drift elimination device, which is different from Embodiment 6 in that: the light output coupling area shared by the two arms of the main interferometer and the two arms of the auxiliary interferometer is realized by a second Y-shaped branch phase modulator 52. At this time, the partial optical path adjustable component of the transmission medium may include the second Y-shaped branch phase modulator 52.

[0073] The technical details and technical effects of this embodiment can be deduced by referring to the foregoing Embodiment 6, and will not be elaborated here.

[0074] Embodiment 8

[0075] As Figure 10 As shown in the figure, on the basis of the technical solution of Embodiment 3, this embodiment further provides the eighth Mach-Zehnder type optical interferometer phase drift elimination device, which is different from Embodiment 3 in that: the light input coupling area of the two arms of the main interferometer and the light output coupling area of the two arms of the auxiliary interferometer are the same first optical coupling area (i.e. Figure 10The optical fiber coupler shown in 1), wherein the first optical coupling region has at least one additional third optical transmission channel; the light emitted by the main light source of the Mach-Zehnder type main interferometer system is input into the first optical coupling region through any one of the at least one third optical transmission channels, so that the light emitted by the main light source is respectively coupled to the two arms of the main interferometer; the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through any one of the at least one third optical transmission channels, or when the at least one third optical transmission channel includes two third optical transmission channels with output optical signal phases being opposite to each other, the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through the two third optical transmission channels, so as to detect, by using the auxiliary detector, an auxiliary phase difference that is positively correlated with the auxiliary optical path difference, wherein the auxiliary interference light refers to the interference result of the light that converges at the two arms of the auxiliary interferometer and is from the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system in the first optical coupling region. Additionally, the light coupling regions on the light output sides of the two arms of the main interferometer and the light coupling regions on the light input sides of the two arms of the auxiliary interferometer are the same second optical coupling region (i.e., Figure 10 The optical fiber coupler shown in 2), wherein the second optical coupling region has at least one additional fourth optical transmission channel; the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through any one of the at least one fourth optical transmission channels, or when the at least one fourth optical transmission channel includes two fourth optical transmission channels with output optical signal phases being opposite to each other, the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through the two fourth optical transmission channels, so as to detect, by using the main detector, a main phase difference that is positively correlated with the optical path difference between the two arms of the main interferometer, wherein the main interference light refers to the interference result of the light that converges at the two arms of the main interferometer and is from the main light source of the Mach-Zehnder type main interferometer system in the second optical coupling region; the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system is input into the second optical coupling region through any one of the at least one fourth optical transmission channels, so that the light emitted by the auxiliary light source is respectively coupled to the two arms of the auxiliary interferometer. As Figure 10As shown, the main difference between this embodiment and Embodiment III is that the positions of the light source 2 (i.e., the auxiliary light source) and the detector 2 (i.e., the auxiliary detector) are swapped. Since there are no Faraday optical devices such as circulators and / or isolators in the two arms of the interferometer, light can be transmitted from left to right or from right to left, thus achieving the purpose of eliminating phase drift. In addition, specifically, the same third optical transmission channel in the at least one third optical transmission channel can be used to transmit the light emitted by the main light source with different wavelengths and the auxiliary interference light, and a wavelength division multiplexer (i.e., Figure 10 the WDM1 shown) is arranged in this same third optical transmission channel to split the light emitted by the main light source and the auxiliary interference light. Moreover, the same fourth optical transmission channel in the at least one fourth optical transmission channel can be used to transmit the light emitted by the auxiliary light source with different wavelengths and the main interference light, and a wavelength division multiplexer (i.e., Figure 10 the WDM2 shown) is arranged in this same fourth optical transmission channel to split the light emitted by the auxiliary light source and the main interference light.

[0076] The technical details and effects of this embodiment can be derived by referring to the aforementioned Embodiment III and will not be elaborated here.

[0077] Embodiment IX

[0078] As Figure 11 shown, on the basis of the technical solution of Embodiment VIII, this embodiment further provides the ninth Mach-Zehnder type optical interferometer phase drift elimination device. The difference from Embodiment VIII is that a circulator (i.e., Figure 11 the first circulator 110 shown) is arranged in the same third optical transmission channel to split the light emitted by the main light source and the auxiliary interference light. Among them, the first port of the circulator is connected to the output port of the main light source of the Mach-Zehnder type main interferometer system, the second port of the circulator is connected to this same third optical transmission channel, the third port of the circulator is connected to the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system. The first port of the circulator is used to transmit the incident light only to the second port of the circulator and emit it. The second port of the circulator is used to transmit the incident light only to the third port of the circulator and emit it. And a circulator (i.e., Figure 11The second circulator 120) shown is used to split the light emitted by the auxiliary light source and the main interference light. Among them, the first port of the circulator is connected to the output port of the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system, the second port of the circulator is connected to the same fourth optical transmission channel, the third port of the circulator is connected to the main detector of the Mach-Zehnder type main interferometer system. The first port of the circulator is used to transmit the incident light only to the second port of the circulator and emit it. The second port of the circulator is used to transmit the incident light only to the third port of the circulator and emit it.

[0079] For the technical details and technical effects of this embodiment, reference can be made to the derivation in the foregoing Embodiment 8, and details will not be repeated here.

[0080] Embodiment Ten

[0081] As Figure 12 shown, on the basis of the technical solutions of Embodiment 1 and Embodiment 9, this embodiment also provides the tenth Mach-Zehnder type optical interferometer phase drift elimination device. The differences from Embodiment 1 and Embodiment 9 are as follows: On the basis of Embodiment 1, the positions of the light source 2 (i.e., the auxiliary light source) and the detector 2 (i.e., the auxiliary detector) are also swapped, and the circulator 1 in the two arms of the interferometer is changed to an optical coupler. That is, the partial optical path of the transmission medium in the main measurement arm includes the partial optical path of the transmission medium from the light coupling area on the light incident side of the two arms of the main interferometer to the optical coupler 7, the partial optical path of the transmission medium from the optical coupler 7 to the collimator 2, the partial optical path of the transmission medium from the collimator 2 to the optical coupler 7, and the partial optical path of the transmission medium from the optical coupler 7 to the light coupling area on the light output side of the two arms of the main interferometer. The partial optical path of the spatial optical path in the main measurement arm includes the partial optical path of the spatial optical path from the collimator 2 to the measured object 100 and the partial optical path of the spatial optical path from the measured object 100 to the collimator 2. The first partial optical path of the spatial optical path includes the partial optical path of the spatial optical path from the collimator 2 to the dichroic mirror 3 and the partial optical path of the spatial optical path from the dichroic mirror 3 to the collimator 2. The second partial optical path of the spatial optical path includes the partial optical path of the spatial optical path from the dichroic mirror 3 to the measured object 100 and the partial optical path of the spatial optical path from the measured object 100 to the dichroic mirror 3. Among them, the dichroic mirror 3 is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system back. In this way, light can also be transmitted from left to right and from right to left, and the purpose of eliminating phase drift can also be achieved.

[0082] To ensure the normal operation of the entire device, it is also necessary to be in the optical coupling area (i.e., Figure 12Corresponding components are added to the outside of the shown optical fiber couplers 1 and 2), that is, preferably, the light emitted by the main light source and the auxiliary interference light, which are of different wavelengths, are transmitted on the same third optical transmission channel among the at least one third optical transmission channels, and a first circulator 110 is arranged in the same third optical transmission channel to split the light emitted by the main light source and the auxiliary interference light. Among them, the first port of the first circulator 110 is connected to the output port of the main light source of the Mach-Zehnder type main interferometer system, the second port of the first circulator 110 is connected to the same third optical transmission channel, the third port of the first circulator 110 is connected to the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system, and a first filter 61 is arranged in the optical path between the third port of the first circulator 110 and the auxiliary detector. The first filter 61 is used to only allow the auxiliary interference light to pass through (that is, mainly filter the light emitted by the main light source reflected back from the optical fiber coupler 1). The first port of the first circulator 110 is used to only transmit the incident light to the second port of the first circulator 110 and emit it. The second port of the first circulator 110 is used to only transmit the incident light to the third port of the first circulator 110 and emit it; and the light emitted by the auxiliary light source and the main interference light, which are of different wavelengths, are transmitted on the same fourth optical transmission channel among the at least one fourth optical transmission channels, and a second circulator 120 is arranged in the same fourth optical transmission channel to split the light emitted by the auxiliary light source and the main interference light. Among them, the first port of the second circulator 120 is connected to the output port of the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system, the second port of the second circulator 120 is connected to the same fourth optical transmission channel, the third port of the second circulator 120 is connected to the main detector of the Mach-Zehnder type main interferometer system, and a second filter 62 is arranged in the optical path between the third port of the second circulator 120 and the main detector. The second filter 62 is used to only allow the main interference light to pass through (that is, mainly filter the light emitted by the auxiliary light source reflected back from the optical fiber coupler 2). The first port of the second circulator 120 is used to only transmit the incident light to the second port of the second circulator 120 and emit it. The second port of the second circulator 120 is used to only transmit the incident light to the third port of the second circulator 120 and emit it. Thus, through the configuration of the first filter 61 and the second filter 62, it is possible to avoid the interference of the light emitted by the main light source on the detection result of the auxiliary detector and the interference of the light emitted by the auxiliary light source on the detection result of the main detector, and ensure the normal operation of the entire device.

[0083] The technical details and technical effects of this embodiment can be derived by referring to the foregoing Embodiment 1 and Embodiment 9, and will not be elaborated here.

[0084] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A device for eliminating phase drift of a Mach-Zehnder type optical interferometer, characterized in that It includes a Mach-Zehnder type main interferometer system, a Mach-Zehnder type auxiliary interferometer system, and a phase drift cancellation processing circuit; The Mach-Zehnder type main interferometer system is used to detect a main phase difference that is positively correlated with the main optical path difference between the two arms of the main interferometer. The two arms of the main interferometer include a main interferometer reference arm and a main interferometer measurement arm. The main optical path difference between the two arms of the main interferometer refers to the difference result between the optical path of the main interferometer measurement arm and the optical path of the main interferometer reference arm. The optical path of the main interferometer measurement arm includes a partial optical path of the main measurement arm transmission medium and a partial optical path of the main measurement arm spatial optical path; The Mach-Zehnder type auxiliary interferometer system is used to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference between the two arms of the auxiliary interferometer. The two arms of the auxiliary interferometer include an auxiliary interferometer reference arm and an auxiliary interferometer measurement arm. The auxiliary optical path difference between the two arms of the auxiliary interferometer refers to the difference result between the optical path of the auxiliary interferometer measurement arm and the optical path of the auxiliary interferometer reference arm. The optical path of the auxiliary interferometer reference arm overlaps with the optical path of the main interferometer reference arm. The optical path of the auxiliary interferometer measurement arm includes a partial optical path of the auxiliary measurement arm transmission medium and a partial optical path of the auxiliary measurement arm spatial optical path; The partial optical path of the main measurement arm transmission medium overlaps with the partial optical path of the auxiliary measurement arm transmission medium. The partial optical path of the main measurement arm spatial optical path includes a first spatial optical path part that completely overlaps with the partial optical path of the auxiliary measurement arm spatial optical path and a second spatial optical path part that does not overlap with the partial optical path of the auxiliary measurement arm spatial optical path. The demarcation point between the first spatial optical path part and the second spatial optical path part is at any position in the partial optical path of the main measurement arm spatial optical path; The input end of the phase drift cancellation processing circuit is electrically connected to the main phase difference detection result output end of the Mach-Zehnder type main interferometer system and the auxiliary phase difference detection result output end of the Mach-Zehnder type auxiliary interferometer system respectively.

2. The Mach-Zehnder optical interferometer phase drift elimination device according to claim 1, wherein The control signal output end of the phase drift cancellation processing circuit is also electrically connected to the controlled end of the adjustable component of the partial optical path of the transmission medium and / or the partial optical path of the spatial optical path in the two arms of the main interferometer. Among them, the adjustable component of the partial optical path of the transmission medium is used to change the partial optical path of the main reference arm transmission medium and / or the partial optical path of the main measurement arm transmission medium, and the adjustable component of the partial optical path of the spatial optical path is used to change the first spatial optical path part.

3. The Mach-Zehnder optical interferometer phase drift elimination device according to claim 2, characterized in that, When the control signal output end of the phase drift cancellation processing circuit is also electrically connected to the controlled end of the adjustable component of the partial optical path of the transmission medium in the two arms of the main interferometer, the adjustable component of the partial optical path of the transmission medium includes a phase modulator, a fiber stretching phase modulator, a temperature control phase modulator, and / or a Y-branch phase modulator; And / or, when the control signal output terminal of the phase drift elimination processing circuit is also electrically connected to the controlled terminal of the optical path length adjustable component in the spatial optical path part of the two arms of the main interferometer, the optical path length adjustable component in the spatial optical path part includes a spatial phase modulator and / or a mechanical moving component for changing the position of the demarcation point between the optical path length of the transmission medium part of the main measurement arm and the optical path length of the spatial optical path part of the main measurement arm.

4. The Mach-Zehnder type optical interferometer phase drift elimination device according to claim 1, characterized in that, The two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light input side optical coupling region, wherein the light input side optical coupling region has at least one additional first optical transmission channel; The light emitted by the main light source of the Mach-Zehnder type main interferometer system is input into the light input side optical coupling region through any one of the at least one first optical transmission channels, so that the light emitted by the main light source is respectively coupled to the two arms of the main interferometer; The light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system is input into the light input side optical coupling region through any one of the at least one first optical transmission channels, so that the light emitted by the auxiliary light source is respectively coupled to the two arms of the auxiliary interferometer; And / or, the two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light output side optical coupling region, wherein the light output side optical coupling region has at least one additional second optical transmission channel; The main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through any one of the at least one second optical transmission channels, or when the at least one second optical transmission channel includes two second optical transmission channels with output optical signals having opposite phases, the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through the two second optical transmission channels, so as to use the main detector to detect the main phase difference positively correlated with the optical path difference between the two arms of the main interferometer, wherein the main interference light refers to the interference result of the light that converges from the two arms of the main interferometer and all comes from the main light source of the Mach-Zehnder type main interferometer system in the light output side optical coupling region; The auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through any one of the at least one second optical transmission channels, or when the at least one second optical transmission channel includes two second optical transmission channels with output optical signals having opposite phases, the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through the two second optical transmission channels, so as to use the auxiliary detector to detect the auxiliary phase difference positively correlated with the auxiliary optical path difference, wherein the auxiliary interference light refers to the interference result of the light that converges from the two arms of the auxiliary interferometer and all comes from the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system in the light output side optical coupling region; And / or, the light coupling regions on the light incident sides of the two arms of the main interferometer and the light coupling regions on the light output sides of the two arms of the auxiliary interferometer are the same first light coupling region, wherein the first light coupling region has at least one additional third light transmission channel; The light emitted by the main light source of the Mach-Zehnder type main interferometer system is input into the first light coupling region through any one of the at least one third light transmission channels, so that the light emitted by the main light source is respectively coupled to the two arms of the main interferometer; The auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through any one of the at least one third light transmission channels, or when the at least one third light transmission channel includes two third light transmission channels with output optical signal phases being opposite to each other, the auxiliary interference light of the Mach-Zehnder type auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system through the two third light transmission channels, so as to use the auxiliary detector to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference, wherein the auxiliary interference light refers to the interference result of the light that converges from the two arms of the auxiliary interferometer and all comes from the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system in the first light coupling region; And / or, the light coupling regions on the light output sides of the two arms of the main interferometer and the light coupling regions on the light incident sides of the two arms of the auxiliary interferometer are the same second light coupling region, wherein the second light coupling region has at least one additional fourth light transmission channel; The main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through any one of the at least one fourth light transmission channels, or when the at least one fourth light transmission channel includes two fourth light transmission channels with output optical signal phases being opposite to each other, the main interference light of the Mach-Zehnder type main interferometer system is input into the main detector of the Mach-Zehnder type main interferometer system through the two fourth light transmission channels, so as to use the main detector to detect a main phase difference that is positively correlated with the optical path difference between the two arms of the main interferometer, wherein the main interference light refers to the interference result of the light that converges from the two arms of the main interferometer and all comes from the main light source of the Mach-Zehnder type main interferometer system in the second light coupling region; The light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system is input into the second light coupling region through any one of the at least one fourth light transmission channels, so that the light emitted by the auxiliary light source is respectively coupled to the two arms of the auxiliary interferometer.

5. The Mach-Zehnder type optical interferometer phase drift elimination device according to claim 4, characterized in that, When using the same first light transmission channel among the at least one first light transmission channel to transmit the light emitted by the main light source and the light emitted by the auxiliary light source with different wavelengths, a wavelength division multiplexer or a dichroic device is arranged in the same first light transmission channel to combine the light emitted by the main light source and the light emitted by the auxiliary light source; And / or, when using the same second optical transmission channel among the at least one second optical transmission channel to transmit the main interference light and the auxiliary interference light with different wavelengths, a wavelength division multiplexer or a dichroic device is arranged in the same second optical transmission channel to split the main interference light and the auxiliary interference light; And / or, when using the same third optical transmission channel among the at least one third optical transmission channel to transmit the light emitted by the main light source and the auxiliary interference light with different wavelengths, a wavelength division multiplexer or a circulator is arranged in the same third optical transmission channel to split the light emitted by the main light source and the auxiliary interference light, wherein the first port of the circulator is connected to the output port of the main light source of the Mach-Zehnder type main interferometer system, the second port of the circulator is connected to the same third optical transmission channel, the third port of the circulator is connected to the auxiliary detector of the Mach-Zehnder type auxiliary interferometer system, the first port of the circulator is used to transmit the incident light only to the second port of the circulator and emit it, and the second port of the circulator is used to transmit the incident light only to the third port of the circulator and emit it; And / or, when using the same fourth optical transmission channel among the at least one fourth optical transmission channel to transmit the light emitted by the auxiliary light source and the main interference light with different wavelengths, a wavelength division multiplexer or a circulator is arranged in the same fourth optical transmission channel to split the light emitted by the auxiliary light source and the main interference light, wherein the first port of the circulator is connected to the output port of the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system, the second port of the circulator is connected to the same fourth optical transmission channel, the third port of the circulator is connected to the main detector of the Mach-Zehnder type main interferometer system, the first port of the circulator is used to transmit the incident light only to the second port of the circulator and emit it, and the second port of the circulator is used to transmit the incident light only to the third port of the circulator and emit it.

6. The Mach-Zehnder type optical interferometer phase drift elimination device according to claim 1, characterized in that, The partial optical path of the transmission medium of the main measurement arm includes the partial optical path of the transmission medium from the light coupling regions on the light incident sides of the two arms of the main interferometer to the first port of the circulator (1), the partial optical path of the transmission medium from the first port of the circulator (1) to the second port of the circulator (1), the partial optical path of the transmission medium from the second port of the circulator (1) to the collimator (2), the partial optical path of the transmission medium from the collimator (2) to the second port of the circulator (1), the partial optical path of the transmission medium from the second port of the circulator (1) to the third port of the circulator (1), and the partial optical path of the transmission medium from the third port of the circulator (1) to the light coupling regions on the light output sides of the two arms of the main interferometer. The partial optical path of the spatial optical path of the main measurement arm includes the partial optical path of the spatial optical path from the collimator (2) to the object under test (100) and the partial optical path of the spatial optical path from the object under test (100) to the collimator (2). The partial optical path of the first spatial optical path includes the partial optical path of the spatial optical path from the collimator (2) to the dichroic mirror (3) and the partial optical path of the spatial optical path from the dichroic mirror (3) to the collimator (2). The partial optical path of the second spatial optical path includes the partial optical path of the spatial optical path from the dichroic mirror (3) to the object under test (100) and the partial optical path of the spatial optical path from the object under test (100) to the dichroic mirror (3). Among them, the first port of the circulator (1) is used to transmit the incident light only to the second port of the circulator (1) and emit it. The second port of the circulator (1) is used to transmit the incident light only to the third port of the circulator (1) and emit it. The dichroic mirror (3) is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect back the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system; Alternatively, the optical path of the transmission medium of the main measurement arm includes the optical path of the transmission medium from the light coupling regions on the incident light sides of the two arms of the main interferometer to the first emission collimator (201) and the optical path of the transmission medium from the first receiving collimator (211) to the light coupling regions on the outgoing light sides of the two arms of the main interferometer. The optical path of the spatial optical path part of the main measurement arm includes the optical path of the spatial optical path from the first emission collimator (201) to the first port of the first spatial circulator (11), the optical path of the spatial optical path from the first port of the first spatial circulator (11) to the second port of the first spatial circulator (11), the optical path of the spatial optical path from the second port of the first spatial circulator (11) to the object under test (100), the optical path of the spatial optical path from the object under test (100) to the second port of the first spatial circulator (11), the optical path of the spatial optical path from the second port of the first spatial circulator (11) to the third port of the first spatial circulator (11), and the optical path of the spatial optical path from the third port of the first spatial circulator (11) to the first receiving collimator (211). The first optical path of the spatial optical path part includes the optical path of the spatial optical path from the first emission collimator (201) to the first port of the first spatial circulator (11), the optical path of the spatial optical path from the first port of the first spatial circulator (11) to the second port of the first spatial circulator (11), the optical path of the spatial optical path from the second port of the first spatial circulator (11) to the dichroic mirror (3), the optical path of the spatial optical path from the dichroic mirror (3) to the second port of the first spatial circulator (11), the optical path of the spatial optical path from the second port of the first spatial circulator (11) to the third port of the first spatial circulator (11), and the optical path of the spatial optical path from the third port of the first spatial circulator (11) to the first receiving collimator (211). The second optical path of the spatial optical path part includes the optical path of the spatial optical path from the dichroic mirror (3) to the object under test (100) and the optical path of the spatial optical path from the object under test (100) to the dichroic mirror (3). Wherein, the first port of the first spatial circulator (11) is used to transmit the incident light only to the second port of the first spatial circulator (11) and emit it. The second port of the first spatial circulator (11) is used to transmit the incident light only to the third port of the first spatial circulator (11) and emit it. The dichroic mirror (3) is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system back; Alternatively, the optical path of the transmission medium of the main measurement arm includes the optical path of the transmission medium from the light coupling regions on the light incident sides of the two arms of the main interferometer to the first emission collimator (201) and the optical path of the transmission medium from the first reception collimator (211) to the light coupling regions on the light output sides of the two arms of the main interferometer. The optical path of the spatial light path of the main measurement arm includes the optical path of the spatial light path from the first emission collimator (201) to the object under test (100) and the optical path of the spatial light path from the object under test (100) to the first reception collimator (211). The first optical path of the spatial light path includes the optical path of the spatial light path from the first emission collimator (201) to the first dichroic mirror (301) and the optical path of the spatial light path from the second dichroic mirror (302) to the first reception collimator (211). The second optical path of the spatial light path includes the optical path of the spatial light path from the first dichroic mirror (301) to the object under test (100) and the optical path of the spatial light path from the object under test (100) to the second dichroic mirror (302). The optical path of the spatial light path of the auxiliary measurement arm includes the first optical path of the spatial light path and the known optical path of the spatial light path from the first dichroic mirror (301) to the second dichroic mirror (302) that does not overlap with the optical path of the spatial light path of the main measurement arm. Among them, the first dichroic mirror (301) is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system to the second dichroic mirror (302). The second dichroic mirror (302) is used to allow the light emitted by the main light source to pass through and reflect the light emitted by the auxiliary light source to the first reception collimator (211). Alternatively, the light coupling regions on the light incident sides of the two arms of the main interferometer and the light coupling regions on the light output sides of the two arms of the auxiliary interferometer are the same first light coupling region, and the light coupling regions on the light output sides of the two arms of the main interferometer and the light coupling regions on the light incident sides of the two arms of the auxiliary interferometer are the same second light coupling region. Among them, the first light coupling region has at least one additional third optical transmission channel, and the second light coupling region has at least one additional fourth optical transmission channel; The light emitted by the main light source of the Mach-Zehnder type main interferometer system is input into the first light coupling region through any one of the at least one third optical transmission channels, so that the light emitted by the main light source is respectively coupled to the two arms of the main interferometer; The light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system is input into the second light coupling region through any one of the at least one fourth optical transmission channels, so that the light emitted by the auxiliary light source is respectively coupled to the two arms of the auxiliary interferometer; The main interference light of the Mach-Zehnder main interferometer system is input into the main detector of the Mach-Zehnder main interferometer system through any one of the at least one fourth optical transmission channel, or when the at least one fourth optical transmission channel includes two fourth optical transmission channels with output optical signal phases being opposite to each other, the main interference light of the Mach-Zehnder main interferometer system is input into the main detector of the Mach-Zehnder main interferometer system through the two fourth optical transmission channels, so as to use the main detector to detect a main phase difference that is positively correlated with the optical path difference between the two arms of the main interferometer. Wherein, the main interference light refers to the interference result of the light that converges from the two arms of the main interferometer and all comes from the main light source of the Mach-Zehnder main interferometer system in the second optical coupling region; The auxiliary interference light of the Mach-Zehnder auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder auxiliary interferometer system through any one of the at least one third optical transmission channel, or when the at least one third optical transmission channel includes two third optical transmission channels with output optical signal phases being opposite to each other, the auxiliary interference light of the Mach-Zehnder auxiliary interferometer system is input into the auxiliary detector of the Mach-Zehnder auxiliary interferometer system through the two third optical transmission channels, so as to use the auxiliary detector to detect an auxiliary phase difference that is positively correlated with the auxiliary optical path difference. Wherein, the auxiliary interference light refers to the interference result of the light that converges from the two arms of the auxiliary interferometer and all comes from the auxiliary light source of the Mach-Zehnder auxiliary interferometer system in the first optical coupling region; The light emitted by the main light source and the auxiliary interference light are transmitted on the same third optical transmission channel among the at least one third optical transmission channel as different wavelengths, and a first circulator (110) is arranged in the same third optical transmission channel to split the light emitted by the main light source and the auxiliary interference light. Wherein, the first port of the first circulator (110) is connected to the output port of the main light source of the Mach-Zehnder main interferometer system, the second port of the first circulator (110) is connected to the same third optical transmission channel, the third port of the first circulator (110) is connected to the auxiliary detector of the Mach-Zehnder auxiliary interferometer system, and a first filter (61) is arranged in the optical path between the third port of the first circulator (110) and the auxiliary detector. The first filter (61) is used to only allow the auxiliary interference light to pass through. The first port of the first circulator (110) is used to only transmit the incident light to the second port of the first circulator (110) and emit it, and the second port of the first circulator (110) is used to only transmit the incident light to the third port of the first circulator (110) and emit it; On the same fourth optical transmission channel among the at least one fourth optical transmission channel, the light emitted by the auxiliary light sources with different wavelengths and the main interference light are transmitted, and a second circulator (120) is arranged in the same fourth optical transmission channel to split the light emitted by the auxiliary light sources and the main interference light, wherein a first port of the second circulator (120) is connected to an output port of the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system, a second port of the second circulator (120) is connected to the same fourth optical transmission channel, a third port of the second circulator (120) is connected to the main detector of the Mach-Zehnder type main interferometer system, and a second filter (62) is arranged in the optical path between the third port of the second circulator (120) and the main detector, and the second filter (62) is used to only allow the main interference light to pass through. The first port of the second circulator (120) is used to only transmit the incident light to the second port of the second circulator (120) and emit it, and the second port of the second circulator (120) is used to only transmit the incident light to the third port of the second circulator (120) and emit it; The partial optical path of the transmission medium of the main measurement arm includes the partial optical path of the transmission medium from the light coupling regions on the light incident sides of the two arms of the main interferometer to the optical coupler (7), the partial optical path of the transmission medium from the optical coupler (7) to the collimator (2), the partial optical path of the transmission medium from the collimator (2) to the optical coupler (7), and the partial optical path of the transmission medium from the optical coupler (7) to the light coupling regions on the light output sides of the two arms of the main interferometer. The partial optical path of the spatial optical path of the main measurement arm includes the partial optical path of the spatial optical path from the collimator (2) to the measured object (100) and the partial optical path of the spatial optical path from the measured object (100) to the collimator (2). The partial optical path of the first spatial optical path includes the partial optical path of the spatial optical path from the collimator (2) to the dichroic mirror (3) and the partial optical path of the spatial optical path from the dichroic mirror (3) to the collimator (2). The partial optical path of the second spatial optical path includes the partial optical path of the spatial optical path from the dichroic mirror (3) to the measured object (100) and the partial optical path of the spatial optical path from the measured object (100) to the dichroic mirror (3), wherein the dichroic mirror (3) is used to allow the light emitted by the main light source of the Mach-Zehnder type main interferometer system to pass through and reflect the light emitted by the auxiliary light source of the Mach-Zehnder type auxiliary interferometer system back.

7. The Mach-Zehnder optical interferometer phase drift elimination device according to claim 1, wherein The optical path of the reference arm of the main interferometer includes the partial optical path of the transmission medium from the light coupling regions on the light incident sides of the two arms of the main interferometer to the second emission collimator (202), the partial optical path of the spatial optical path from the second emission collimator (202) to the second reception collimator (212), and the partial optical path of the transmission medium from the second reception collimator (212) to the light coupling regions on the light output sides of the two arms of the main interferometer.

8. The Mach-Zehnder type optical interferometer phase drift elimination device according to claim 7, characterized in that, The optical path of the reference arm of the auxiliary interferometer overlapping with the optical path of the reference arm of the main interferometer includes the following partial overlapping cases: The optical path of the spatial optical path portion from the second emission collimator (202) to the second reception collimator (212) includes the optical path of the spatial optical path portion from the second emission collimator (202) to the first port of the second spatial circulator (12), the optical path of the spatial optical path portion from the first port of the second spatial circulator (12) to the second port of the second spatial circulator (12), the optical path of the spatial optical path portion from the second port of the second spatial circulator (12) to the third dichroic mirror (303), the optical path of the spatial optical path portion from the third dichroic mirror (303) to the reference mirror (200), the optical path of the spatial optical path portion from the reference mirror (200) to the third dichroic mirror (303), the optical path of the spatial optical path portion from the third dichroic mirror (303) to the second port of the second spatial circulator (12), the optical path of the spatial optical path portion from the second port of the second spatial circulator (12) to the third port of the second spatial circulator (12), and the optical path of the spatial optical path portion from the third port of the second spatial circulator (12) to the second reception collimator (212). Among them, the optical path of the spatial optical path portion from the third dichroic mirror (303) to the reference mirror (200) and the optical path of the spatial optical path portion from the reference mirror (200) to the third dichroic mirror (303) are respectively known optical paths of the spatial optical path portions that do not overlap with the optical path of the reference arm of the main interferometer.

9. The Mach-Zehnder optical interferometer phase drift elimination device according to claim 1, characterized in that , The two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light coupling area on the light input side, where the light coupling area on the light input side is implemented by a Y-shaped branch phase modulator; And / or, the two arms of the main interferometer and the two arms of the auxiliary interferometer share the same light coupling area on the light output side, where the light coupling area on the light output side is implemented by a Y-shaped branch phase modulator.

10. A working method of the phase drift elimination device of the Mach-Zehnder type optical interferometer as described in claim 2, characterized in that, Executed by the phase drift cancellation processing circuit, including: According to the auxiliary phase difference detection result from the Mach-Zehnder type auxiliary interferometer system, controlling the optical path adjustable component of the transmission medium portion and / or the optical path adjustable component of the spatial optical path portion in the two arms of the main interferometer to change the optical path, so that the phase drift of the Mach-Zehnder type auxiliary interferometer system is always at zero or a certain fixed phase, so as to lock the phase drift of the Mach-Zehnder type main interferometer system at zero or a certain fixed phase; Or, obtaining the main optical path difference by converting the main phase difference of the Mach-Zehnder type main interferometer system, and obtaining the auxiliary optical path difference by converting the auxiliary phase difference of the Mach-Zehnder type auxiliary interferometer system, and then subtracting the auxiliary optical path difference from the main optical path difference to eliminate the inherent phase drift of the Mach-Zehnder type main interferometer and obtain the actual measurement value.

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