A method and system for fiber measurement based on multi-time observation structure

Abstract

This invention discloses a fiber optic measurement method and system based on a multi-time observation structure, relating to the fields of fiber optic sensing and spectral measurement technology. The method includes: applying modulation drive to a light source to output a tuned optical signal whose wavelength varies with time; inputting the tuned optical signal into a fiber optic sensor device, causing the measured physical quantity to act on the sensing structure; the spectral response of the sensing structure changes under the combined action of the tuned optical signal and the measured physical quantity, outputting an optical signal exhibiting multiple time responses in the time domain; converting the optical signal into a time-domain electrical signal, and extracting multiple time parameters of the same spectral response of the sensing structure from the time-domain electrical signal to obtain multi-time observation data; constructing a time criterion based on the multi-time observation data; and calculating the measured physical quantity according to the changes in the time criterion to obtain the measurement result. This method transforms single-time measurement into multi-time measurement, enabling the differentiation and suppression of changes in the measured quantity and system time shift.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing and spectral measurement technology, specifically to a fiber optic measurement method and system based on a multi-time observation structure. Background Technology

[0002] Fiber optic sensor demodulators are the core equipment in fiber optic sensing systems and are widely used in fields such as fiber Bragg gratings, interferometric sensing, and spectral measurement.

[0003] Existing demodulation methods are typically based on the principle of wavelength scanning. This involves tuning the light source or equivalent tuning structure to change the wavelength of the output light over time, thus converting the spectral response of the sensor or the object under test into a time-domain signal. However, while the demodulation result is usually presented in wavelength form, the underlying implementation often relies on the mapping relationship between time and wavelength. This means that the wavelength information is inferred by detecting the temporal position of the spectral response during the scanning process. Therefore, these methods are usually based on time parameters, and their measurement accuracy is directly affected by the accuracy of time measurement and the stability of the time reference. Currently, a single time parameter is typically used for measurement, such as the occurrence time of a certain spectral response during the scanning process or the time position where a preset condition is met.

[0004] However, the above methods have the following drawbacks in practical applications: (1) Strong dependence on time reference: Since the time parameter is directly used to characterize wavelength information, the measurement results are highly dependent on the stability of the time reference; in actual systems, factors such as trigger level changes, trigger jitter, electronic link delay changes, and optical path propagation delay fluctuations will all introduce the overall offset of the time axis, thus causing errors in the measurement results; (2) Indistinguishability of single observations: A single time parameter is simultaneously affected by the change of the measured quantity and the system time offset. Without additional reference, it is difficult to distinguish the sources of the two, and it is easy to misjudge the system drift as the change of the measured quantity. This reduces measurement reliability; (3) The problem is more prominent under high time resolution or weak signal conditions: In high-speed scanning or high-precision measurement scenarios, the time change caused by the measured quantity is small, while the system time offset remains at a certain level. At this time, the two may be on the same order of magnitude, which makes the time reference instability more significant on the measurement results, and may even become the main factor limiting measurement accuracy; (4) Strong dependence on external reference: In order to reduce the above influence, existing systems usually rely on high-stability triggering systems, precision clocks or introduce gas absorption lines and other standard etalons for absolute wavelength calibration, thereby increasing system complexity and implementation cost.

[0005] In summary, current fiber optic measurements of a single time parameter are affected by both the change in the measurand and the system time offset. Without additional references, it is difficult to distinguish the sources of these two factors, and system drift is easily misjudged as a change in the measurand, thus reducing measurement reliability. Summary of the Invention

[0006] To address the shortcomings of existing technologies where a single time parameter is simultaneously affected by both the change in the measurand and the system time offset, making it difficult to distinguish the sources of the two without additional references, and easily leading to misjudging system drift as a change in the measurand, thus reducing measurement reliability, this invention proposes an optical fiber measurement method and system based on a multi-time observation structure. By generating at least two time correspondences for the same spectral response within a single modulation cycle, and constructing a time criterion based on these multiple time correspondences, a single-time measurement is transformed into a multi-time measurement, enabling the differentiation and suppression of changes in the measurand and system time offset, thereby solving the problems existing in the prior art.

[0007] A fiber optic measurement method based on a multi-time observation structure includes the following steps: Apply modulation drive to the light source so that its output wavelength changes with time; A tuned optical signal is input into an optical fiber sensor that is subjected to the physical quantity being measured. The spectral response of the optical fiber sensor changes under the combined action of the tuned optical signal and the physical quantity being measured, and outputs an optical signal that exhibits multiple time responses in the time domain. The optical signal is converted into a time-domain electrical signal, and multiple time parameters corresponding to the same spectral response characteristics of the optical fiber sensor at different time positions are extracted from the time-domain electrical signal to obtain multi-time observation data. A time criterion is constructed based on multi-time observation data; the measured physical quantity is calculated according to the changes in the time criterion to obtain the measurement result.

[0008] Furthermore, during the modulation driving process of the light source, by adjusting the tuning trajectory of its wavelength change over time, the same wavelength range is covered multiple times within a modulation cycle, so that the same spectral response of the optical fiber sensor corresponds to at least two different time positions.

[0009] Furthermore, the wavelength tuning method is one or more combinations of continuous linear tuning, continuous nonlinear tuning, discrete step tuning, segmented tuning, or periodic tuning.

[0010] Furthermore, the continuous linear tuning completes a forward tuning process from the minimum wavelength to the maximum wavelength and a reverse tuning process from the maximum wavelength back to the minimum wavelength within one modulation cycle.

[0011] Furthermore, the continuous nonlinear tuning method is a sinusoidal tuning form; the sinusoidal tuning form enables the wavelength to complete a forward tuning process from the wavelength minimum to the wavelength maximum and a reverse tuning process from the wavelength maximum back to the wavelength minimum within one cycle, and the same wavelength range is scanned multiple times, thereby realizing a multi-time correspondence.

[0012] Furthermore, the time criterion is calculated by using multi-time observation data to make the same spectral response correspond to multiple time positions in the time domain, specifically including time difference criterion, time combination criterion, or combination operation criterion based on multi-time observation data.

[0013] The present invention also includes a fiber optic measurement system based on a multi-time observation structure, comprising: A light source modulation unit is used to apply modulation drive to the light source so that it outputs a tuned light signal whose wavelength changes with time. The fiber optic sensing unit is used to input a tuned optical signal into a fiber optic sensor device that is acted upon by the measured physical quantity. The spectral response of the fiber optic sensor device changes under the combined action of the tuned optical signal and the measured physical quantity, and outputs an optical signal that exhibits multiple time responses in the time domain. A photoelectric detection unit is used to convert the optical signal into a time-domain electrical signal; The data acquisition and processing unit is used to extract multiple time parameters at different time positions corresponding to the same spectral response characteristics of the optical fiber sensor from the time-domain electrical signal, so as to obtain multi-time observation data. The measurement unit is used to construct time criteria based on multi-time observation data; and to calculate the measured physical quantity and obtain the measurement result based on the changes in the time criteria.

[0014] Furthermore, the light source modulation unit is driven by a single trigger signal, enabling the light source to complete forward and reverse wavelength tuning within one modulation cycle, thereby obtaining a paired time response in the time domain.

[0015] Furthermore, the fiber optic sensor includes, but is not limited to, fiber Bragg gratings, fiber optic interferometers, fiber-optic connected gas absorption units, and other sensing structures with spectral response characteristics.

[0016] This invention provides a fiber optic measurement method based on a multi-time observation structure, which has the following advantages: This invention inputs a tuned optical signal into an optical fiber sensor, causing the measured physical quantity and the tuned optical signal to act together on the spectral response of the sensing structure. It outputs an optical signal exhibiting multiple time responses in the time domain, and then extracts multiple time parameters from the same spectral response to construct a time criterion. This effectively separates the overall offset of the system's time axis from the changes caused by the measured physical quantity, significantly reducing the dependence of the measurement results on unstable time reference factors such as trigger jitter, electronic link delay, and optical path propagation delay. Simultaneously, the multi-time parameter observation method based on the same spectral response makes the changes in the measured quantity and system drift distinguishable, solving the fundamental problem of the difficulty in distinguishing between the two in traditional single-time parameter measurements. Thus, it achieves high-precision, high-stability self-calibration measurements without relying on external reference channels or highly stable clocks, making it particularly suitable for high-speed scanning and weak signal detection scenarios. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the fiber optic measurement system architecture based on a multi-time observation structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the light source tuning method in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the multi-time observation measurement principle in an embodiment of the present invention; Figure 4 This is a schematic diagram of the fiber optic measurement method based on a multi-time observation structure in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] This invention proposes an optical fiber measurement method based on a multi-time observation structure. This method transforms a single time measurement into a multi-time measurement by generating at least two time correspondences for the same wavelength within a single modulation period and constructing a time criterion based on the multiple time correspondences, thereby achieving the distinction and suppression of changes in the measured quantity and system time offset.

[0020] like Figure 4 As shown, the method specifically includes the following steps: S1. Apply modulation drive to the light source so that its wavelength changes with time, and make the same wavelength correspond to at least two different time positions within a single modulation cycle.

[0021] S2. The tuned light source is output to the fiber optic sensor or spectral sensing structure, causing the spectral response of the fiber optic sensor or spectral sensing structure to form multiple time responses in the time domain. The fiber optic sensor or spectral sensing structure includes, but is not limited to, fiber Bragg gratings, fiber optic interferometers, fiber-optic connected gas absorption units, and other sensing structures with identifiable spectral response characteristics.

[0022] S3. Extract time parameters corresponding to the same spectral response position from multiple time responses to form at least one set of multi-time observation data.

[0023] S4. Construct time criteria based on multi-time observation data, including time difference criteria, time combination criteria, or other criteria based on multiple time parameters.

[0024] S5. Solve for the measured physical quantity based on the change of the time criterion.

[0025] In the multi-time observation structure of this invention, changes in the measured physical quantity will cause differential changes in the corresponding spectral response across different time correspondences, with the system time offset mainly manifested as an overall shift of the time axis. By constructing a time criterion based on multiple time parameters, the overall time offset can be eliminated or separated during criterion calculation, thereby reducing the dependence of the measurement results on the stability of the time reference and achieving self-calibration measurement without the need for additional references.

[0026] The present invention has the following features and benefits: (1) The method transforms measurement based on a single time parameter into measurement based on multiple time parameters, thereby improving the identifiability of the measurement; (2) The common-mode offset of the time axis is effectively suppressed by multiple time criteria, thereby improving the measurement stability; (3) Self-calibration of the system time offset is achieved without the need for an additional reference channel; (4) It is applicable to high-speed scanning and weak signal detection scenarios, which is beneficial to improving the measurement reliability; (5) It reduces the dependence on high-stability timing systems and external calibration devices, which is beneficial to simplifying the system structure.

[0027] Based on the above methods, the present invention proposes the following embodiments: Example 1: This example provides a fiber optic measurement method based on a multi-time observation structure, including the following steps: S1. The light source is modulated by the light source modulation unit, so that the output wavelength changes with time. Within one modulation cycle, the same wavelength range is covered multiple times in the time domain by the tuning trajectory design, thus providing a basis for multi-time observation.

[0028] The wavelength tuning process is not limited to a specific implementation method. It can be implemented by continuous tuning, discrete step tuning, periodic or non-periodic tuning, etc. As long as the same spectral response feature can be achieved to correspond to multiple time positions, it is within the protection scope of this invention.

[0029] In a preferred embodiment, the light source modulation unit is driven by a single trigger signal, enabling the light source to complete forward and reverse wavelength tuning within one modulation cycle, thereby forming a paired time response.

[0030] S2. Input the tuned optical signal to the fiber optic sensing unit so that the measured physical quantity acts on the sensor and causes a change in its spectral characteristics. The change in spectral characteristics is converted into a corresponding time-domain response change through the wavelength-time mapping relationship established in step S1. The measured physical quantity includes temperature, strain, pressure, vibration, refractive index, displacement, gas concentration or other physical parameters that can cause changes in spectral characteristics.

[0031] The fiber optic sensing unit can be a reflective or transmissive structure, including but not limited to fiber Bragg gratings, fiber interferometers, fiber-optic connected gas absorption units, and other sensing structures with recognizable spectral response characteristics.

[0032] S3. The optical signal is detected by the photoelectric detection unit and converted into an electrical signal.

[0033] Among them, the electrical signal is a time-domain signal, reflecting the time mapping relationship of the spectral response during the tuning process.

[0034] S4. Acquire and process the time-domain electrical signal, extract multiple time parameters corresponding to the same spectral response characteristics, and form multi-time observation data.

[0035] Furthermore, multiple time parameters are combined to construct time criteria; time criteria include, but are not limited to, time difference criteria, time center criteria, time average criteria, time weighted combination criteria, or other combination criteria constructed based on multiple time parameters.

[0036] Time difference criterion: ; Time center criterion: ; Weighted combination: ; in, and These represent the time parameters corresponding to the same spectral response characteristic at different observation locations at different times; Indicates the time center criterion; This indicates the weighted combination criterion; and This is a weighting coefficient, and its value can be set according to specific measurement needs.

[0037] S5. Measurement Result Acquisition: Based on the change of the time criterion, calculate the measured physical quantity and obtain the measurement result.

[0038] In multi-time observation structures, changes in the measured physical quantity will cause changes in the relative relationships between corresponding time parameters, and system time drift is mainly manifested as an overall shift of the time axis. By constructing a criterion based on multiple time parameters, the influence of time drift on measurement results can be effectively suppressed, thereby improving the stability and identifiability of the measurement.

[0039] Example 2: This example provides a schematic diagram of a light source tuning method applicable to the present invention, such as... Figure 2 The diagram illustrates how to achieve multi-time observations under different tuning trajectories.

[0040] In this invention, by designing a tuning trajectory for the wavelength of the light source to change over time, the same wavelength range is covered multiple times within a modulation cycle, thereby generating multiple time correspondences for the same spectral response in the time domain.

[0041] (1) Linear reciprocating tuning mode: like Figure 2 As shown in (a), the wavelength of the light source changes linearly with time, completing the transition from the minimum wavelength λ within one modulation cycle. min Towards the maximum wavelength λ max The tuning process, and the tuning process of λ max Return to λ min The tuning process.

[0042] In this tuning mode, the same wavelength corresponds to two different time positions during forward tuning (λ increasing) and reverse tuning (λ decreasing), thus forming a paired time response.

[0043] (2) Continuous nonlinear tuning mode: like Figure 2 As shown in (b), the wavelength of the light source changes continuously and non-linearly with time, such as in a sinusoidal tuning mode. In this tuning method, the wavelength also undergoes an increasing and decreasing process within one cycle, allowing the same wavelength range to be scanned multiple times, thus achieving a multi-time correspondence. Compared to linear tuning, this method exhibits a continuous change in the tuning rate, allowing for optimization of the time distribution characteristics according to specific needs.

[0044] (3) Segmented or discrete tuning methods: like Figure 2 As shown in (c), the wavelength of the light source varies in segments or discrete steps over time. In this tuning method, through multi-stage or segmented tuning, the same wavelength range is accessed multiple times within one cycle, thus enabling multi-time observation. This method is suitable for digital control or segmented modulation systems and offers flexibility in implementation.

[0045] It should be noted that the above tuning methods are merely illustrative, and this invention does not limit the specific tuning form. As long as the same spectral response can correspond to at least two time positions within one modulation period, thereby forming multi-time observation data, it falls within the protection scope of this invention.

[0046] Example 3: This example provides an explanation of the measurement principle based on multi-time observation, such as... Figure 3 The diagram illustrates the measurement mechanism of the present invention in the presence of time drift.

[0047] (1) Traditional single-time parameter measurement method like Figure 3 As shown in (a), in traditional measurement methods based on a single time parameter, the time position corresponding to a certain spectral response is usually selected as the measurement parameter, denoted as . .

[0048] Ideally, this time parameter is only related to the measured physical quantity; however, in practical systems, due to factors such as trigger jitter, electronic delay, or changes in the optical path, the time axis will shift overall. Let this shift be... The measured time parameter then becomes .

[0049] As can be seen, a single time parameter simultaneously contains both the measured information and the system time drift. Therefore, it is impossible to distinguish between measurement changes and system drift, thus affecting measurement accuracy and stability.

[0050] (2) Multi-time observation measurement method of the present invention: like Figure 3 As shown in (b), in this invention, a multi-time observation structure is used to make the same spectral response correspond to multiple time positions in the time domain, denoted as... Ideally, these two time parameters together reflect the measured physical quantity.

[0051] First, construct the time difference criterion: .

[0052] When the system has time drift hour: .

[0053] The time difference then becomes: .

[0054] It can be seen that: Time difference criterion D Unaffected by overall time drift.

[0055] Further construct the time center criterion: .

[0056] In the presence of time drift: .

[0057] It can be seen that: Time Center C It reflects the overall time drift.

[0058] The above analysis shows that: Time difference criterion D Related to the measured physical quantity and unaffected by time drift; time center criterion C It reflects the system time drift and can be used for drift monitoring or compensation; therefore, by constructing multi-time observations and extracting time criteria, the changes in the measured physical quantity and the system time drift can be effectively separated, thereby improving the stability and reliability of the measurement.

[0059] Based on the same inventive concept, this invention also provides a fiber optic measurement system based on a multi-time observation structure for implementing the above method, such as... Figure 1 As shown, it includes: The light source modulation unit is used to apply modulation drive to the light source so that its output wavelength changes with time.

[0060] The fiber optic sensing unit is used to input a tuned optical signal into a fiber optic sensor device that is acted upon by the measured physical quantity. The spectral response of the fiber optic sensor device changes under the combined action of the tuned optical signal and the measured physical quantity, and outputs an optical signal that exhibits multiple time responses in the time domain.

[0061] The photoelectric detection unit is used to convert optical signals into time-domain electrical signals.

[0062] The data acquisition and processing unit is used to extract multiple time parameters corresponding to the same spectral response characteristics of the fiber optic sensor from the time-domain electrical signal at different time locations, thereby obtaining multi-time observation data.

[0063] The measurement unit is used to construct time criteria based on multi-time observation data; and to calculate the measured physical quantity and obtain the measurement result based on the changes in the time criteria.

[0064] The tuning method of the light source modulation unit is not limited to a specific implementation form, including but not limited to: continuous wavelength tuning, discrete step tuning, single or multiple scans, periodic or non-periodic tuning. As long as the same spectral response can produce at least two corresponding relationships in the time domain, it is within the protection scope of this invention. Preferably, the light source modulation unit is driven by a single trigger signal to enable the light source to complete forward and reverse wavelength tuning within one modulation cycle, thereby obtaining a paired time response in the time domain.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fiber optic measurement method based on a multi-time observation structure, characterized in that, Includes the following steps: Apply modulation drive to the light source so that its output wavelength changes with time; A tuned optical signal is input into an optical fiber sensor that is subjected to the physical quantity being measured. The spectral response of the optical fiber sensor changes under the combined action of the tuned optical signal and the physical quantity being measured, and outputs an optical signal that exhibits multiple time responses in the time domain. The optical signal is converted into a time-domain electrical signal, and multiple time parameters corresponding to the same spectral response characteristics of the optical fiber sensor at different time positions are extracted from the time-domain electrical signal to obtain multi-time observation data. A time criterion is constructed based on multi-time observation data; the measured physical quantity is calculated according to the changes in the time criterion to obtain the measurement result.

2. The fiber optic measurement method based on a multi-time observation structure according to claim 1, characterized in that, During the modulation drive process of the light source, by adjusting the tuning trajectory of its wavelength change over time, the same wavelength range is covered multiple times within a modulation cycle, so that the same spectral response of the optical fiber sensor corresponds to at least two different time positions.

3. The fiber optic measurement method based on a multi-time observation structure according to claim 1, characterized in that, The wavelength tuning method is one or more combinations of continuous linear tuning, continuous nonlinear tuning, discrete step tuning, segmented tuning, or periodic tuning.

4. The fiber optic measurement method based on a multi-time observation structure according to claim 1, characterized in that, The continuous linear tuning completes a forward tuning process from the minimum wavelength to the maximum wavelength and a reverse tuning process from the maximum wavelength back to the minimum wavelength within one modulation cycle.

5. The fiber optic measurement method based on a multi-time observation structure according to claim 1, characterized in that, The continuous nonlinear tuning method is a sinusoidal tuning form; the sinusoidal tuning form enables the wavelength to complete a forward tuning process from the minimum wavelength to the maximum wavelength and a reverse tuning process from the maximum wavelength back to the minimum wavelength within one cycle, and the same wavelength range is scanned multiple times, thereby realizing a multi-time correspondence.

6. The fiber optic measurement method based on a multi-time observation structure according to claim 1, characterized in that, The time criterion is calculated by using multi-time observation data to make the same spectral response correspond to multiple time positions in the time domain. Specifically, it includes time difference criterion, time combination criterion, or combination operation criterion based on multi-time observation data.

7. A fiber optic measurement system based on a multi-time observation structure, characterized in that, include: A light source modulation unit is used to apply modulation drive to the light source so that it outputs a tuned light signal whose wavelength changes with time. The fiber optic sensing unit is used to input a tuned optical signal into a fiber optic sensor device that is acted upon by the measured physical quantity. The spectral response of the fiber optic sensor device changes under the combined action of the tuned optical signal and the measured physical quantity, and outputs an optical signal that exhibits multiple time responses in the time domain. A photoelectric detection unit is used to convert the optical signal into a time-domain electrical signal; The data acquisition and processing unit is used to extract multiple time parameters at different time positions corresponding to the same spectral response characteristics of the optical fiber sensor from the time-domain electrical signal, so as to obtain multi-time observation data. The measurement unit is used to construct time criteria based on multi-time observation data; and to calculate the measured physical quantity and obtain the measurement result based on the changes in the time criteria.

8. The fiber optic measurement system based on a multi-time observation structure according to claim 7, characterized in that, The light source modulation unit is driven by a single trigger signal, enabling the light source to complete forward and reverse wavelength tuning within one modulation cycle, thereby obtaining a paired time response in the time domain.

9. The fiber optic measurement system based on a multi-time observation structure according to claim 7, characterized in that, The fiber optic sensor devices include, but are not limited to, fiber Bragg gratings, fiber optic interferometers, fiber-optic connected gas absorption units, and other sensing structures with spectral response characteristics.

Images