An adjustable optical fiber delay line delay calibration device and method based on laser circular polarization displacement measurement

Abstract

The present invention discloses a calibration device and method for the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement, comprising: generating an interference signal through a Michelson interferometer module, wherein a fiber optic mirror that does not change the phase is used for the reference mirror, and a Faraday rotator mirror that can change the phase of light by 90° is used for the measurement mirror. The two cooperate to achieve a 90° phase difference between the measurement signal and the reference signal, and then enter the laser circular polarization displacement measurement module. The interference fringe processing method based on the switching of sine and cosine signals is used to process the signal to obtain the phase change amount, and the total displacement amount can be obtained through the relational expression. The optical delay amount can be calculated from the total displacement amount to realize the measurement and calibration of the delay amount of the adjustable optical fiber delay line.

Description

Technical Field

[0001] The present invention belongs to the technical field of geometric quantity measurement, and particularly relates to an adjustable optical fiber delay line delay calibration device and method based on laser circular polarization displacement measurement. Background Art

[0002] The delay-adjustable optical fiber delay line is composed of input and output optical fiber collimators and a motion device, and is used to project light into free space and collect it into the optical fiber again. By changing the propagation distance of light through the motion device, the optical path delay time can be controlled. By controlling the relative distance (one-way) between the input and output optical ports, or the distance traveled by light when passing through a movable mirror (two-way), the distance traveled by light in free space can be accurately controlled. The essence is to accurately measure the spatial distance value and the displacement within a variable range.

[0003] At present, the performance test methods of optical fiber delay lines mainly estimate by methods such as time reflection and displacement comparison. Since the absolute time delay measurement accuracy is low and cannot meet the technical requirements, there is still a lack of effective calibration methods so far, and there is a blank in its traceability technology, which severely restricts the improvement of the quality and accuracy of optical fiber delay line-related products. As a result, it is difficult to achieve a qualitative breakthrough in many key technologies or key technical indicators in related industry applications. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes an adjustable optical fiber delay line delay calibration device and method based on laser circular polarization displacement measurement to solve the problems existing in the above prior art.

[0005] To achieve the above object, the present invention provides an adjustable optical fiber delay line delay calibration device based on laser circular polarization displacement measurement, including:

[0006] A laser for emitting laser light to a Michelson interferometer module;

[0007] A moving module for controlling the optical delay amount by moving to generate an optical path difference;

[0008] A Michelson interferometer module for changing the optical path difference during the movement of the moving module to generate an interference signal containing a phase difference, wherein the movement process is driven by the moving module;

[0009] A processing module for analyzing and processing the interference signal to complete calibration.

[0010] Optionally, the Michelson interferometer module includes: an optical fiber coupler, an optical fiber mirror, a first collimator, a Faraday rotator mirror, and a reflecting prism.

[0011] Optionally, the optical fiber coupler is a 50 / 50 optical fiber coupler.

[0012] Optionally, in the Michelson interferometer module, after the moving module completes the movement, the optical path generated by the laser emitted by the laser in the Michelson interferometer module includes: a displacement reference optical path and a displacement measurement optical path; wherein,

[0013] The direction of the displacement reference optical path includes: an optical fiber coupler, an optical fiber mirror;

[0014] The direction of the displacement measurement optical path includes: an optical fiber coupler, a first collimator, a reflection prism, a Faraday rotator mirror.

[0015] Optionally, in the Michelson interferometer module, the laser signal reflected back by the optical fiber mirror is a reference signal, and the laser signal reflected back by the Faraday rotator mirror is a measurement signal, and the phase difference between the reference signal and the measurement signal is 90°.

[0016] Optionally, the processing module includes a plurality of collimators, a plurality of analyzers, and a plurality of photodetectors; wherein,

[0017] The photodetector is configured to analyze and process the interference signal after passing through the collimator and the analyzer to obtain the optical path difference, and perform processing based on the optical path difference to obtain the time delay amount, and complete the calibration based on the time delay amount.

[0018] The present invention also provides a calibration method for the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement, and the method includes:

[0019] After the moving module completes the movement, the laser emits laser light, controls the delay amount of the light by moving, generates an optical path difference, obtains an interference signal containing a phase difference through the optical path, analyzes and processes the interference signal, and completes the calibration.

[0020] Optionally, the optical path includes: an optical fiber coupler, an optical fiber mirror, a first collimator, a Faraday rotator mirror, and a reflection prism.

[0021] The present invention also provides a computer terminal device, including:

[0022] One or more processors;

[0023] A memory coupled to the processor for storing one or more programs;

[0024] When the one or more programs are executed by the one or more processors, the one or more processors implement each step of a calibration method for the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement.

[0025] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, each step of a calibration method for the delay amount of an adjustable fiber optic delay line based on laser circular polarization displacement measurement is implemented.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] An adjustable fiber optic delay line delay amount calibration device and method based on laser circular polarization displacement measurement provided by the present invention. The device includes: a laser for emitting a laser to a Michelson interferometer module; a moving module for generating an optical path difference by controlling the delay amount of light; a Michelson interferometer module for generating an interference signal containing a phase difference during the movement of the moving module; and a processing module for analyzing and processing the interference signal to complete calibration. The present invention uses the laser circular polarization displacement measurement method for signal processing and demodulation, and adopts the interference fringe processing method of switching between sine and cosine signals, improving the measurement accuracy. The present invention uses a Michelson interferometer with an all-fiber structure to convert the displacement measurement result into the optical propagation time delay amount, innovating and enriching the design of laser displacement interference. The present invention combines a Michelson interferometer and a method based on laser circular polarization displacement measurement to achieve the purpose of calibrating the optical delay amount of an adjustable fiber optic delay line. Description of the Drawings

[0028] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0029] Figure 1 It is a schematic diagram of the measurement and calibration device according to an embodiment of the present invention;

[0030] Reference numerals: 1. Laser; 2. Optical isolator; 3. Fiber optic coupler; 4. Fiber optic mirror; 5. First collimator; 6. Faraday rotator mirror; 7. Reflecting prism; 8. Guide rail; 9. Second collimator; 10. Quarter-wave plate; 11. First ordinary beam splitter prism; 12. Second ordinary beam splitter prism; 13. First polarizer; 14. Second polarizer; 15. Third polarizer; 16. First photodetector; 17. Second photodetector; 18. Third photodetector. Detailed Embodiments

[0031] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail this application.

[0032] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0033] Embodiment 1

[0034] As Figure 1 shown, in this embodiment, a calibration device for the delay amount of an adjustable fiber optic delay line based on laser circular polarization displacement measurement is provided, including:

[0035] A laser 1 for emitting laser light to the Michelson interferometer module;

[0036] A moving module for generating an optical path difference by controlling the delay amount of light through movement;

[0037] A Michelson interferometer module for generating an interference signal containing a phase difference during the movement process, where the movement process is driven by the moving module;

[0038] A processing module for analyzing and processing the interference signal to complete calibration.

[0039] As an optional implementation manner, when the moving module controls the delay amount of light through movement, it is to simulate the fiber optic delay line and provide an optical path difference for the Michelson interferometer; specifically, during the measurement process, the upper computer in the moving module controls the guide rail 8 to move to generate an optical path difference.

[0040] As an optional implementation manner, the processing module uses the method of laser circular polarization displacement measurement for processing, including: adopting a signal processing method of sine-cosine switching to reduce the error caused by A / D and DC signal noise and improve the measurement accuracy; demodulating the measured signal to realize the calibration of the delay amount of the adjustable fiber optic delay line.

[0041] Specifically, an optical isolator 2 is connected between the laser 1 and the Michelson interferometer module.

[0042] As an optional implementation manner, the Michelson interferometer module includes: an optical fiber coupler 3, an optical fiber mirror 4, a first collimator 5, a Faraday rotator mirror 6, and a reflecting prism 7.

[0043] As an optional implementation manner, the optical fiber coupler 3 is any one of a 50 / 50 optical fiber coupler, a 70 / 30 optical fiber coupler, and an 80 / 20 optical fiber coupler, preferably a 50 / 50 optical fiber coupler.

[0044] As an alternative embodiment, in the Michelson interferometer module, during the movement of the moving module, the optical path generated by the laser 1 in the Michelson interferometer module includes: a displacement reference optical path and a displacement measurement optical path; where

[0045] The direction of the displacement reference optical path includes: an optical fiber coupler 3 and an optical fiber mirror 4;

[0046] The direction of the displacement measurement optical path includes: an optical fiber coupler 3, a first collimator 5, a reflection prism 7, and a Faraday rotator mirror 6.

[0047] Among them, the optical fiber mirror 4 does not change the phase, while the Faraday rotator mirror 6 can change the phase by 90°.

[0048] As an alternative embodiment, in the Michelson interferometer module, the laser signal reflected back by the optical fiber mirror 4 is a reference signal, and the laser signal reflected back by the Faraday rotator mirror 6 is a measurement signal, and the phase difference between the reference signal and the measurement signal is 90°.

[0049] As an additional embodiment, the interference signal formed by the reference optical path and the measurement optical path passes through the laser circular polarization interference nano-displacement measurement system to obtain the displacement of the guide rail 8, and then the corresponding delay amount is calculated, that is, the optical delay amount of the optical fiber delay line.

[0050] As an alternative embodiment, the processing module includes a plurality of collimators, a plurality of analyzers, and a plurality of photodetectors; where

[0051] The photodetector is used to analyze and process the interference signal after passing through the collimator and analyzer to obtain the optical path difference, and based on the optical path difference, the time delay amount is obtained, and the calibration is completed based on the time delay amount.

[0052] As an additional embodiment, the processing module includes a second collimator 9, a quarter-wave plate 10, a first ordinary beam splitter prism 11, a first analyzer 13, a first photodetector 16, a second ordinary beam splitter prism 12, a second analyzer 14, a third analyzer 15, a second photodetector 17, and a third photodetector 18.

[0053] Next, in combination with the specific devices included in the processing module, the optical path in the processing module will be described:

[0054] As an additional embodiment, the measurement optical signal direction of the first photodetector 16 includes: an optical fiber coupler 3, a second collimator 9, a quarter-wave plate 10, a first ordinary beam splitter prism 11, a first analyzer 13, and a first photodetector 16.

[0055] The optical signal path of the second photodetector 17 includes: an optical fiber coupler 3, a second collimator 9, a quarter-wave plate 10, a first ordinary beam splitter prism 11, a second ordinary beam splitter prism 12, a second analyzer 14, and a second photodetector 17.

[0056] The optical signal path of the third photodetector 18 includes: an optical fiber coupler 3, a second collimator 9, a quarter-wave plate 10, a first ordinary beam splitter prism 11, a second ordinary beam splitter prism 12, a third analyzer 15, and a third photodetector 18.

[0057] As an additional implementation, the light transmission direction of the first analyzer 13 is parallel to the horizontal direction, the light transmission direction of the second analyzer 14 forms an angle of 45° with the horizontal direction, and the light transmission direction of the third analyzer 15 forms an angle of 90° with the horizontal direction.

[0058] Based on this, an adjustable optical fiber delay line delay calibration device based on laser circular polarization displacement measurement provided by an embodiment of the present invention includes: a laser for emitting laser light to a Michelson interferometer module; a moving module for generating an optical path difference by controlling the delay of light through movement; a Michelson interferometer module for generating an interference signal with a phase difference during the movement of the moving module; and a processing module for analyzing and processing the interference signal to complete calibration. The present invention uses a laser circular polarization displacement measurement method for signal processing and demodulation, and uses an interference fringe processing method of switching sine and cosine signals, improving the measurement accuracy. The present invention uses a fully fiber-optic structure Michelson interferometer, converts the displacement measurement result into an optical propagation time delay, and innovates and enriches the design of laser displacement interference. The present invention combines a Michelson interferometer and a laser circular polarization displacement measurement method to achieve the purpose of calibrating the optical delay of an adjustable optical fiber delay line.

[0059] Embodiment 2

[0060] Based on the same inventive concept, the present invention also provides an adjustable optical fiber delay line delay calibration method based on laser circular polarization displacement measurement. The adjustable optical fiber delay line delay calibration method provided by the present invention is described below. The adjustable optical fiber delay line delay calibration method described below can be mutually referred to the adjustable optical fiber delay line delay calibration device described above. The method includes:

[0061] After the moving module completes the movement, the laser emits laser light, generates an optical path difference by controlling the delay of light through movement, obtains an interference signal with a phase difference through the optical path, and analyzes and processes the interference signal to complete calibration.

[0062] As an alternative embodiment, the optical path includes: an optical fiber coupler 3, an optical fiber mirror 4, a first collimator 5, a Faraday rotator mirror 6, and a reflecting prism 7.

[0063] The specific process includes:

[0064] Step 1, adjustment of the initial state before measurement:

[0065] When the laser light source module is operating normally, the displacement value of the guide rail is set to zero through the host computer. The laser light source module uses a laser.

[0066] Step 2, displacement measurement:

[0067] The laser 1 generates a beam of laser light and couples it into the optical fiber. After passing through the optical isolator, it is divided into two beams of light by the optical fiber coupler 3. One beam of light exits the optical fiber and is incident on the reference mirror, i.e., the optical fiber mirror 4, and then reflected back into the optical fiber. The other beam of light passes through the reflecting prism 7 and is incident on the measurement mirror, i.e., the Faraday rotator mirror 6. After reflection, the phase changes by 90° and then re-enters the optical fiber. After the two beams of laser light are coupled at the optical fiber coupler 3, they enter the displacement measurement module. During the measurement process, the guide rail is moved by the host computer in the moving module to generate an optical path difference. Among them, the optical fiber coupler 3 is preferably a 50:50 optical fiber coupler, and any one of a 70 / 30 optical fiber coupler and an 80 / 20 optical fiber coupler can also be selected.

[0068] Step 3, signal processing:

[0069] The three signals measured by the photodetector first pass through a proportional operational amplifier circuit to make the amplitudes of the AC components of the three signals equal; then, the first and second signals and a DC quantity pass through an addition and subtraction operation circuit, and the second and third signals and another DC quantity pass through an addition and subtraction operation circuit to eliminate the DC component in the output signal. Then, the signal is processed using an interference fringe processing method based on the switching of sine and cosine signals to obtain the phase change amount, and the total displacement amount can be obtained through the relational expression. The optical delay amount can be calculated from the total displacement amount.

[0070] As an alternative embodiment, the signals received by the three photodetectors are respectively:

[0071]

[0072] Among them, a1, a2, and a3 are respectively the DC components of the three signals, b1, b2, and b3 are respectively the amplitudes of the AC components of the three signals, θ = 4π / λx, and x represents the displacement amount.

[0073] The three signals first pass through a proportional operational amplifier circuit to make the amplitudes of the AC components equal. Let the output signals be D 11 、D 12 、D 13。Then, the first and second signals and a DC current are passed through an addition and subtraction circuit, and the second and third signals and another DC current are passed through an addition and subtraction circuit.

[0074] As an additional implementation, let the output signals be S1 and S2 respectively, and the formula is:

[0075]

[0076] S2 = bcos(θ + 3π / 4) - bcos(θ + π / 4) + (a6 - a5 + c2) = -Acosθ (3)

[0077] where b is the amplitude of the AC signal, θ is the phase, and A is a4, a5, a6 are the DC components of D 11 , D 12 , D 13 , and c1 = a5 - a4, c2 = a6 - a5.

[0078] As an additional implementation, the signal is processed by an interference fringe processing method based on the switching of sine and cosine signals. The total phase change amount is π / 4 multiplied by the value n of the counter, plus the phase θ that is less than π / 4 in one counting period. The phase θ that is less than one counting period is calculated using the corrected θ formula.

[0079] The expression for the total displacement x is:

[0080]

[0081] where λ is the laser wavelength, θ is the phase, and π / 4 is the counting period.

[0082] Step 4, time delay measurement:

[0083] The relationship between the displacement x measured by signal demodulation and the time delay Δt can be used to calculate the time delay.

[0084] As an additional implementation, the relationship between the displacement x measured by the signal demodulation and the time delay Δt is:

[0085]

[0086] where c is the speed of light, and the time delay can be calculated from Equation (5).

[0087] The present invention generates an interference signal through a Michelson interferometer module. Among them, a fiber optic mirror that does not change the phase is used as the reference mirror, and a Faraday rotation mirror that can change the phase of light by 90° is used as the measurement mirror. The two cooperate to achieve a 90° phase difference between the measurement signal and the reference signal, and then enter the laser circular polarization displacement measurement module. The signal is processed using an interference fringe processing method based on the switching of sine and cosine signals to obtain the phase change amount, and the total displacement amount can be obtained through the relational expression. From the total displacement amount, the optical delay amount can be calculated to realize the measurement and calibration of the delay amount of the tunable fiber optic delay line.

[0088] It should be understood that a calibration method for the delay amount of a tunable fiber optic delay line based on laser circular polarization displacement measurement provided by an embodiment of the present invention has all the advantages of the calibration device for the delay amount of a tunable fiber optic delay line based on laser circular polarization displacement measurement provided by the above embodiment.

[0089] The present invention also provides a computer terminal device, including:

[0090] One or more processors;

[0091] A memory, coupled to the processor, for storing one or more programs;

[0092] When the one or more programs are executed by the one or more processors, the one or more processors implement each step of a calibration method for the delay amount of a tunable fiber optic delay line based on laser circular polarization displacement measurement.

[0093] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, each step of a calibration method for the delay amount of a tunable fiber optic delay line based on laser circular polarization displacement measurement is implemented.

[0094] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A delay calibration device for an adjustable optical fiber delay line based on laser circular polarization displacement measurement, characterized in that: include: A laser (1), used for emitting laser light to the Michelson interferometer module; A moving module, used for controlling the delay amount of light by moving to generate an optical path difference; A Michelson interferometer module, used to generate an interference signal containing a phase difference during a moving process, wherein the moving process is driven by the moving module; A processing module is used to analyze and process the interference signal and complete the calibration; The processing module includes a plurality of collimators, a plurality of analyzers and a plurality of photodetectors; wherein, The photoelectric detector is used to analyze and process the interference signal after passing through the collimator and the analyzer to obtain the optical path difference, and to process based on the optical path difference to obtain the time delay, and to complete the calibration based on the time delay; The processing module comprises a second collimator (9), a quarter wave plate (10), a first ordinary beam splitter prism (11), a first polarizer (13), a first photodetector (16), a second ordinary beam splitter prism (12), a second polarizer (14), a third polarizer (15), a second photodetector (17) and a third photodetector (18); The direction of the measurement light signal of the first photodetector (16) includes: a fiber coupler (3), a second collimator (9), a quarter-wave plate (10), a first ordinary beam splitter (11), a first polarizer (13), and a first photodetector (16); The measurement optical signal direction of the second photoelectric detector (17) includes: an optical fiber coupler (3), a second collimator (9), a quarter-wave plate (10), a first ordinary beam splitter prism (11), a second ordinary beam splitter prism (12), a second polarizer (14), and a second photoelectric detector (17); The measurement optical signal direction of the third photoelectric detector (18) includes: a fiber coupler (3), a second collimator (9), a quarter wave plate (10), a first ordinary beam splitter prism (11), a second ordinary beam splitter prism (12), a third polarizer (15), and a third photoelectric detector (18); The light transmission direction of the first polarizer (13) is parallel to the horizontal direction, the light transmission direction of the second polarizer (14) is 45 degrees to the horizontal direction, and the light transmission direction of the third polarizer (15) is 90 degrees to the horizontal direction.

2. The device according to claim 1, characterized in that The Michelson interferometer module comprises: a fiber coupler (3), a fiber reflector (4), a first collimator (5), a Faraday rotation mirror (6) and a reflective prism (7).

3. The device according to claim 2, characterized in that The optical fiber coupler (3) is a 50 / 50 optical fiber coupler (3).

4. The device according to claim 1, characterized in that In the Michelson interferometer module, after the moving module completes the movement, the optical path generated by the laser light emitted by the laser (1) in the Michelson interferometer module includes: a displacement reference optical path and a displacement measurement optical path; wherein, The displacement reference optical path includes: an optical fiber coupler (3) and an optical fiber reflector (4); The displacement measurement optical path includes: an optical fiber coupler (3), a first collimator (5), a reflecting prism (7), and a Faraday rotating mirror (6).

5. The device according to claim 4, characterized in that In the Michelson interferometer module, the laser signal reflected back by the optical fiber reflector (4) is the reference signal, and the laser signal reflected back by the Faraday rotator (6) is the measurement signal. The phase difference between the reference signal and the measurement signal is 90°.

6. A method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement, implemented in the device for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement according to any one of claims 1 to 5, characterized in that: The method comprises: The laser emits laser light, and the delay of the light is controlled by moving the moving module, thereby generating an optical path difference. The interference signal containing the phase difference is obtained through the optical path, and the interference signal is analyzed and processed to complete the calibration. The interference signal containing phase difference is obtained through the optical path, and the process of analyzing and processing the interference signal includes: The signals received by the three photodetectors are: Among them, a1, a2, a3 are the DC components of the three signals respectively, b1, b2, b3 are the AC component amplitudes of the three signals respectively, θ=4π / λx, x represents the displacement; The three signals first pass through the proportional amplifier circuit to make the amplitude of the AC component equal, and the output signals are D 11 , D 12 , D 13 , then the first and second signals and a DC quantity are passed through an addition and subtraction circuit, and the second and third signals and another DC quantity are passed through an addition and subtraction circuit; Let the output signals be S1 and S2 respectively, the formula is: S2=bcos(θ+3π / 4)-bcos(θ+π / 4)+(a6-a5+c2)=-Acosθ (3) Where b is the amplitude of the AC signal, θ is the phase, and A is a4, a5, a6 are D 11 , D 12 , D 13 The DC component, c1 = a5-a4, c2 = a6-a5; The signal is processed by the interference fringe processing method based on the switching of sine and cosine signals. The total phase change is π / 4 multiplied by the counter value n, plus the phase θ that is less than one counting cycle π / 4, where the phase θ that is less than one counting cycle is calculated using the modified θ formula; The total displacement x is expressed as: Among them, λ is the laser wavelength, θ is the phase, and π / 4 is the counting period.

7. The method according to claim 6, characterized in that The optical path includes: a fiber coupler, a fiber reflector, a first collimator, a Faraday rotating mirror and a reflecting prism.

8. A computer terminal device, characterized in that: include: one or more processors; A memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the various steps of the method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement as described in any one of claims 6 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, each step of the method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement as described in any one of claims 6 to 7 is implemented.

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