Adjustable optical fiber delay line delay amount calibration device and method based on laser circular polarization displacement measurement

Abstract

The invention discloses an adjustable optical fiber delay line delay amount calibration device and method based on laser circular polarization displacement measurement, and the method comprises the steps: generating an interference signal through a Michelson interferometer module, enabling a reference mirror to be an optical fiber reflector which does not change the phase, enabling a measurement mirror to be a Faraday rotating mirror which can enable the phase of light to be changed by 90 degrees, and enabling the phase of light to be changed by 90 degrees; a 90-degree phase difference between a measurement signal and a reference signal is achieved through cooperation of the measurement signal and the reference signal, then the measurement signal enters the laser circular polarization displacement measurement module, the signals are processed through an interference fringe processing method based on sine and cosine signal switching, the phase variation is obtained, and the total displacement can be obtained through a relational expression. And the optical delay amount can be calculated according to the total displacement amount, so that the delay amount of the adjustable optical fiber delay line can be measured and calibrated.

Description

Technical Field

[0001] The invention belongs to the technical field of geometric quantity testing, and in particular relates to a device and method for calibrating the delay quantity of an adjustable optical fiber delay line based on laser circular polarization displacement measurement. Background Art

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

[0003] At present, the performance test method of optical fiber delay line is mainly estimated by 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. There is a gap in its traceability technology, which seriously limits the quality and accuracy improvement of optical fiber delay line related products. As a result, it is difficult to make qualitative breakthroughs in many key technologies or key technical indicators used in related industries. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a device and method for calibrating the delay amount of an adjustable optical fiber delay line 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 a delay calibration device for an adjustable optical fiber delay line based on laser circular polarization displacement measurement, comprising:

[0006] A laser, used for emitting laser light to the Michelson interferometer module;

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

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

[0009] The processing module is used to analyze and process the interference signal to complete the calibration.

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

[0011] Optionally, the fiber optic coupler is a 50 / 50 fiber optic 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 displacement reference optical path includes: a fiber coupler and a fiber reflector;

[0014] The displacement measurement optical path includes: a fiber coupler, a first collimator, a reflecting prism, and a Faraday rotation mirror.

[0015] Optionally, in the Michelson interferometer module, the laser signal reflected back by the fiber optic reflector is a reference signal, and the laser signal reflected back by the Faraday rotator 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 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.

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

[0019] After the mobile module completes its movement, the laser emits a laser, controls the delay of the light by movement, 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: a fiber coupler, a fiber reflector, a first collimator, a Faraday rotation mirror and a reflecting prism.

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

[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 various steps of a method for calibrating 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 having a computer program stored thereon. When the computer program is executed by a processor, the computer program implements various steps of a method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement.

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

[0027] The present invention provides a device and method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement. The device includes: a laser for emitting laser light to a Michelson interferometer module; a moving module for controlling the delay amount of light by moving to generate an optical path difference; 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 adopts a laser circular polarization displacement measurement method for signal processing and demodulation, and adopts an interference fringe processing method of switching sine and cosine signals to improve the measurement accuracy. The present invention adopts a Michelson interferometer with an all-fiber structure to convert the displacement measurement result into the light propagation time delay amount, which innovates and enriches 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 light delay amount of an adjustable optical fiber delay line. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0030] Figure numerals: 1. laser; 2. optical isolator; 3. fiber coupler; 4. fiber reflector; 5. first collimator; 6. Faraday rotator; 7. reflecting prism; 8. guide rail; 9. second collimator; 10. quarter wave plate; 11. first ordinary beam splitter; 12. second ordinary beam splitter; 13. first polarizer; 14. second polarizer; 15. third polarizer; 16. first photodetector; 17. second photodetector; 18. third photodetector. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0033] Embodiment 1

[0034] like Figure 1 As shown, this embodiment provides a delay calibration device for an adjustable optical fiber delay line based on laser circular polarization displacement measurement, comprising:

[0035] Laser 1, used for emitting laser light to the Michelson interferometer module;

[0036] A moving module, used for controlling the delay amount of light by moving to generate an optical path difference;

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

[0038] The processing module is used to analyze and process the interference signal to complete the calibration.

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

[0040] As an optional implementation, the processing module adopts laser circular polarization displacement measurement to perform processing, including: using a sine-cosine switching signal processing method to reduce the errors caused by A / D and DC signal noise and improve measurement accuracy; demodulating the measured signal to realize adjustable optical fiber delay line delay calibration.

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

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

[0043] As an optional implementation, 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 optional implementation, in the Michelson interferometer module, during the movement of the moving module, the optical path generated by the laser emitted by the laser 1 in the Michelson interferometer module includes: a displacement reference optical path and a displacement measurement optical path; wherein,

[0045] The displacement reference optical path includes: a fiber coupler 3 and a fiber reflector 4;

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

[0047] The fiber optic reflector 4 does not change the phase, but the Faraday rotator 6 can change the phase by 90°.

[0048] As an optional implementation, in the Michelson interferometer module, the laser signal reflected back by the fiber optic reflector 4 is the reference signal, and the laser signal reflected back by the Faraday rotator 6 is the measurement signal, and the phase difference between the reference signal and the measurement signal is 90°.

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

[0050] As an optional implementation, the processing module includes a plurality of collimators, a plurality of polarizers and a plurality of photodetectors; wherein,

[0051] 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.

[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 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.

[0053] Next, the optical path in the processing module is described in conjunction with the components specifically included in the processing module:

[0054] As an additional implementation, 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 prism 11 , a first polarizer 13 , and a first photodetector 16 .

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

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

[0057] As an additional implementation, 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° to the horizontal direction, and the light transmission direction of the third polarizer 15 is 90° to the horizontal direction.

[0058] Based on this, an embodiment of the present invention provides an adjustable optical fiber delay line delay calibration device based on laser circular polarization displacement measurement, comprising: a laser for emitting laser light to a Michelson interferometer module; a mobile module for controlling the delay of light by movement to generate an optical path difference; a Michelson interferometer module for generating an interference signal containing a phase difference during the movement of the mobile module; and a processing module for analyzing and processing the interference signal to complete calibration. The present invention adopts a laser circular polarization displacement measurement method for signal processing and demodulation, and adopts an interference fringe processing method of switching sine and cosine signals to improve the measurement accuracy. The present invention adopts a Michelson interferometer with an all-fiber structure to convert the displacement measurement result into the light propagation time delay, which 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 light delay of an adjustable optical fiber delay line.

[0059] Embodiment 2

[0060] Based on the same inventive concept, the present invention also provides a method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement. The method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement provided by the present invention is described below. The method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement described below and the device for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement described above can correspond to each other. The method includes:

[0061] After the mobile module completes its movement, the laser emits a laser, controls the delay of the light by movement, 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.

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

[0063] The specific process includes:

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

[0065] When the laser light source module works normally, the displacement value of the guide rail is adjusted to zero by the host computer, and the laser light source module adopts a laser.

[0066] Step 2, displacement measurement:

[0067] 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 through the optical fiber coupler 3. One beam of light is emitted from the optical fiber and then directed to the reference mirror, i.e., the optical fiber reflector 4, and then reflected back into the optical fiber. The other beam of light passes through the reflecting prism 7 and then directed to the measuring mirror, i.e., the Faraday rotator 6. After reflection, the phase changes by 90° and then re-enters the optical fiber. After the two laser beams are coupled at the optical fiber coupler 3, they enter the displacement measurement module. During the measurement process, the upper computer controls the guide rail in the mobile module to move, generating 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 the proportional operational amplifier circuit to make the AC component amplitudes of the three signals equal; then, the first and second signals and the DC quantity pass through the addition and subtraction circuit, and the second and third signals and another DC quantity pass through the addition and subtraction circuit, so that the DC component is eliminated from the output signal. Then, 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, and the total displacement can be obtained through the relationship. The optical delay can be solved by the total displacement.

[0070] As an optional implementation, the signals received by the three photodetectors are:

[0071]

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

[0073] The three signals first pass through the proportional amplifier circuit to make the amplitude of the AC component equal. Let the output signals be D 11 , D 12 , D 13Then the first and second signals and a DC flow are passed through the addition and subtraction circuit.

[0075] The second and third signals and another DC quantity pass through the addition and subtraction circuit.

[0076] As an additional implementation method, let the output signals be S1 and S2 respectively, and the formula is:

[0077]

[0078] S2=bcos(θ+3π / 4)-bcos(θ+π / 4)+(a6-a5+c2)=-Acosθ (3)

[0079] Where b is the amplitude of the AC signal, θ is the phase, and A is a4, a5, a6 are D 11 , D12, D13's DC components, c1=a5-a4, c2=a6-a5.

[0082] As an addable implementation method, the signal is processed by an interference fringe processing method based on switching sine and cosine signals, and 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.

[0083] The total displacement x is expressed as:

[0084]

[0085] Among them, λ is the laser wavelength, θ is the phase, and π / 4 is the counting period.

[0086] Step 4, time delay measurement:

[0087] The time delay can be calculated from the relationship between the displacement x and the time delay Δt measured by signal demodulation.

[0088] As an additional implementation manner, the relationship between the displacement x and the time delay Δt measured by the signal demodulation is:

[0089]

[0090] Where c is the speed of light, and the time delay can be calculated by equation (5).

[0091] The present invention generates interference signals through a Michelson interferometer module, wherein a reference mirror uses an optical fiber reflector that does not change the phase, and a measuring mirror uses a Faraday rotator that can change the phase of light by 90°, and 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, and use an interference fringe processing method based on sine and cosine signal switching to process the signal to obtain a phase change, and the total displacement can be obtained through a relationship. The light delay can be solved from the total displacement to achieve measurement and calibration of the delay of an adjustable optical fiber delay line.

[0092] It should be understood that the method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement provided in an embodiment of the present invention has all the advantages of the device for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement provided in the above-mentioned embodiment.

[0093] The present invention also provides a computer terminal device, comprising:

[0094] one or more processors;

[0095] A memory, coupled to the processor, for storing one or more programs;

[0096] When the one or more programs are executed by the one or more processors, the one or more processors implement various steps of a method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement.

[0097] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the computer program implements various steps of a method for calibrating the delay amount of an adjustable optical fiber delay line based on laser circular polarization displacement measurement.

[0098] The above are only preferred specific implementations 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 a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on 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) for emitting laser light to a 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; The processing module is used to analyze and process the interference signal to complete the calibration.

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. The device according to claim 1, characterized in that 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.

7. A method for calibrating the delay of an adjustable optical fiber delay line based on laser circular polarization displacement measurement, characterized in that: The method comprises: The laser emits a laser, and the delay of the light is controlled by moving the moving module, thereby generating an optical path difference. An interference signal containing a phase difference is obtained through the optical path, and the interference signal is analyzed and processed to complete the calibration.

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

9. 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 7 to 8.

10. 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 7 to 8 is implemented.

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