Temperature-compensated optical fiber speckle displacement sensor

Abstract

The application discloses a temperature compensation type optical fiber speckle displacement sensor and relates to the technical field of optical measurement, solves the technical problem that the prior art is often difficult to effectively distinguish speckle changes caused by displacement and temperature, and limits the application of the optical fiber speckle displacement sensor in a high temperature difference environment; a plurality of speckle data under a standard ambient temperature T is acquired; a speckle change amount is generated according to the ambient temperature and the speckle data of a reference channel; measurement speckle data of a measurement channel is generated according to the speckle change amount and the speckle data of the measurement channel; a displacement amount is generated according to the measurement speckle data; an alarm signal is generated according to the speckle data; the change of the ambient temperature on the speckle pattern is monitored by designing the reference channel; the speckle pattern of the sensor is updated through the change of the speckle pattern of the reference channel, the measurement accuracy of the sensor is prevented from being reduced due to the change of the ambient temperature, and meanwhile, the application range of the optical fiber speckle displacement sensor is wider.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical measurement, and specifically relates to a temperature-compensated optical fiber speckle displacement sensor. BACKGROUND

[0002] A sensor is a device that converts a non-electric parameter into a measurable electric signal output. Through a sensitive element and a conversion element, a specific measured signal is converted into a certain usable signal according to a certain rule and is output to meet the requirements of information transmission, processing, recording, display and control. A sensor can sense physical quantities such as force, temperature, light, sound, chemical composition, etc., and can convert these physical quantities into voltage, current or the on-off of a circuit according to a certain rule. An optical fiber speckle displacement sensor is a displacement measuring device based on the laser speckle effect, which can be applied to industrial automation, structural health monitoring and precision manufacturing fields.

[0003] However, changes in the ambient temperature can cause slight changes in the optical path length inside the optical fiber, which in turn causes the speckle pattern to drift or deform, seriously affecting the accuracy and stability of the measurement results. The prior art often cannot effectively distinguish between the speckle changes caused by displacement and the speckle changes caused by temperature changes, limiting the application of the optical fiber speckle displacement sensor in high-temperature-difference environments. Therefore, the optical fiber speckle displacement sensor still needs further improvement. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a temperature-compensated optical fiber speckle displacement sensor to solve the technical problem that the prior art often cannot effectively distinguish between the speckle changes caused by displacement and temperature, limiting the application of the optical fiber speckle displacement sensor in high-temperature-difference environments.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a temperature-compensated optical fiber speckle displacement sensor, comprising: a data acquisition device, a data analysis device, a warning device and a data storage device.

[0006] The data acquisition device: acquires the ambient temperature, displacement data and speckle data through a data acquisition device;

[0007] The data analysis device: acquires a plurality of speckle data under a standard ambient temperature T; generates a speckle change amount according to the ambient temperature and the speckle data of the reference channel; generates measured speckle data of the measurement channel according to the speckle change amount and the speckle data of the measurement channel; generates a displacement amount according to the measured speckle data; and generates an alarm signal according to the speckle data;

[0008] The warning device: makes a prompt according to the alarm signal and contacts the management personnel.

[0009] The present application introduces the speckle pattern change caused by temperature through the above steps, obtains the final speckle pattern of the sensor according to the speckle pattern of the sensor at the current temperature and the speckle pattern change, realizes the temperature compensation of the fiber speckle displacement sensor, and makes the application range of the fiber speckle displacement sensor wider.

[0010] Further, the speckle change amount is generated according to the environmental temperature and the speckle data of the reference channel, including:

[0011] The environmental temperature T of the reference channel and the light intensity distribution I of the speckle pattern in the corresponding speckle data are acquired in real time CKT (x, y) and the standard environmental temperature BT and the light intensity distribution I of the speckle pattern in the corresponding speckle data CKBT (x, y);

[0012] The speckle change amount ΔI in the reference channel is calculated by the formula ΔI = I CKT (x, y) - I CKBT (x, y).

[0013] Further, the measurement speckle data of the measurement channel is generated according to the speckle change amount and the speckle data of the measurement channel, including:

[0014] The speckle change amount ΔI of the reference channel and the light intensity distribution I of the speckle pattern in the speckle data of the measurement channel at the environmental temperature T are acquired CLT (x, y);

[0015] The light intensity distribution I CLBT (x, y) = I CLT (x, y) - ΔI of the speckle pattern at the standard environmental temperature in the measurement channel is calculated by the formula CLBT (x, y).

[0016] Further, the displacement amount is generated according to the measurement speckle data, including:

[0017] The light intensity distribution of the speckle pattern in the measurement speckle data is acquired

[0018] The light intensity distribution is input into a displacement calibration model to obtain a displacement amount; the displacement calibration model is constructed by an artificial intelligence model.

[0019] Further, the displacement calibration model is constructed by an artificial intelligence model, including:

[0020] A plurality of historical light intensity distributions and corresponding displacement amounts are acquired

[0021] The plurality of historical light intensity distributions and corresponding displacement amounts are divided into training data, verification data and test data; the training data, verification data and test data are preprocessed to obtain a training set, a verification set and a test set;

[0022] Choose an artificial intelligence model as the base model;

[0023] The base model is trained on the training set, and the learning rate and hyperparameters are adjusted on the validation set to obtain the pre-trained model.

[0024] By validating the pre-trained model on the test set, a displacement calibration model was finally obtained, with the input being the light intensity distribution and the output being the displacement amount.

[0025] Furthermore, the step of generating an alarm signal based on speckle data includes:

[0026] Within the time period SJ, several ambient temperatures T and corresponding speckle data were acquired for the reference channel, along with the intensity distribution I of the speckle pattern. CK (x, y);

[0027] Through the formula ΔI CKs =I CKs (x, y) - I CK(s-1) (x, y) Calculate the change in light intensity distribution ΔI of the speckle pattern of the reference channel within the time period SJ. CK ;

[0028] Through the formula ΔT s =T s -T s-1 Calculate the change in ambient temperature ΔT of the reference channel over the time period SJ. s Where s = 1, 2, ..., S; S represents the total number of times data is collected within SJ;

[0029] Determine whether the absolute value of the change in light intensity distribution is greater than the light intensity change threshold;

[0030] Yes, when the absolute value of the change in ambient temperature is greater than the temperature change threshold, no operation is performed; otherwise, a reference channel fault alarm signal is generated.

[0031] No, do nothing.

[0032] Compared with the prior art, the beneficial effects of this application are as follows: It acquires several speckle data points at a standard ambient temperature T; generates speckle change based on the ambient temperature of the reference channel and the speckle data; generates measurement speckle data for the measurement channel based on the speckle change and the speckle data of the measurement channel; generates displacement based on the measurement speckle data; and generates an alarm signal based on the speckle data. The design of the reference channel monitors changes in the speckle pattern caused by ambient temperature. By updating the sensor's speckle pattern based on changes in the reference channel's speckle pattern, the accuracy of the sensor's measurement is prevented from decreasing due to changes in ambient temperature, and the applicability of the fiber optic speckle displacement sensor is broadened. Attached Figure Description

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0034] Fig. 1 A schematic diagram of a temperature-compensated optical fiber speckle displacement sensor according to the present application;

[0035] Fig. 2 A method flowchart of a temperature-compensated optical fiber speckle displacement sensor according to the present application. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] Please refer to Figs. 1-2 The first aspect of the present application provides a temperature-compensated optical fiber speckle displacement sensor, which comprises a data acquisition device, a data analysis device, a warning device and a data storage device.

[0038] The data acquisition device acquires environmental temperature, displacement data and speckle data through a data acquisition device, which includes a camera and a temperature sensor, etc.

[0039] The data analysis device acquires a plurality of speckle data under a standard environmental temperature T; generates a speckle change amount according to the environmental temperature and the speckle data of the reference channel, wherein the speckle change amount refers to the change of the light intensity distribution of the speckle pattern; generates measurement speckle data of the measurement channel according to the speckle change amount and the speckle data of the measurement channel, wherein the measurement speckle data refers to the speckle data after temperature compensation of the sensor; generates a displacement amount according to the measurement speckle data, wherein the displacement amount refers to the displacement value of the sensor; generates an alarm signal according to the speckle data; the value of the standard environmental temperature T is set according to experience, and in the present embodiment, T is set to 25℃.

[0040] The warning device makes a prompt according to the alarm signal and contacts the management personnel; the alarm signal includes a reference channel failure alarm signal, etc.

[0041] In the present embodiment, two cameras are used to collect data of different channels during speckle data collection; in another embodiment, the same camera is used to monitor the speckle patterns of two channels, reducing the number of cameras and increasing the compactness of the system.

[0042] In the present embodiment, the speckle variation is generated according to the reference channel's ambient temperature and speckle data, including:

[0043] The ambient temperature T of the reference channel and the light intensity distribution I of the speckle pattern in the corresponding speckle data are obtained in real time CKT (x, y) and the standard ambient temperature BT and the light intensity distribution I of the speckle pattern in the corresponding speckle data CKBT (x, y);

[0044] The speckle variation AI in the reference channel is calculated by the formula AI = I CKT (x, y) - I CKBT (x, y); The greater the difference between the ambient temperature T and the standard ambient temperature BT of the light intensity distribution of the speckle pattern in the reference channel, the greater the absolute value of the speckle variation in the reference channel.

[0045] In the present embodiment, a reference channel is designed, and the structure of the reference channel and the sensor is completely consistent. The optical fiber of the reference channel is in a straightened state without obvious bending, so the speckle pattern of the reference channel will be affected by temperature, which will affect the compensation to the sensor, thereby improving the application temperature range of the optical fiber speckle displacement sensor.

[0046] In the present embodiment, the measurement speckle data of the measurement channel is generated according to the speckle variation and the speckle data of the measurement channel, including:

[0047] The speckle variation AI of the reference channel and the light intensity distribution I of the speckle pattern in the speckle data of the measurement channel at the ambient temperature T are obtained CLT (x, y); The measurement channel is the position of the multi-mode optical fiber in the sensor, and the speckle pattern obtained by the measurement channel is the speckle pattern obtained by the sensor;

[0048] The light intensity distribution I CLBT (x, y) = I CLT (x, y) - AI of the speckle pattern at the standard ambient temperature in the measurement channel is calculated CLBT (x, y); In the case of AI determination, I CLBT (x, y) increases with the increase of I CLT (x, y).

[0049] In the present embodiment, the displacement is generated according to the measurement speckle data, including:

[0050] The light intensity distribution of the speckle pattern in the measurement speckle data is obtained;

[0051] The light intensity distribution is input into the displacement calibration model to obtain a displacement amount; the displacement calibration model is constructed through an artificial intelligence model.

[0052] The displacement calibration model in the embodiment is constructed through an artificial intelligence model, including:

[0053] A plurality of historical light intensity distributions and corresponding displacement amounts are obtained;

[0054] The plurality of historical light intensity distributions and corresponding displacement amounts are divided into training data, verification data and test data; the training data, verification data and test data are preprocessed to obtain a training set, a verification set and a test set;

[0055] An artificial intelligence model is selected as a base model; the artificial intelligence model includes a convolutional neural network model; the ratio between the training set, the test set and the verification set is 7:2:1;

[0056] The base model is trained through the training set, and a learning rate and hyperparameters are adjusted on the verification set to obtain a pre-trained model;

[0057] The pre-trained model is verified on the test set, and finally a displacement calibration model with the light intensity distribution as input and the displacement amount as output is obtained.

[0058] The embodiment generates an alarm signal according to the speckle data, including:

[0059] The environmental temperature T of the reference channel and the light intensity distribution I of the speckle pattern in the corresponding speckle data are obtained within a time period SJ CK (x, y); the time period SJ is set according to experience;

[0060] The light intensity distribution change amount ΔI of the speckle pattern of the reference channel within the time period SJ is calculated through the formula ΔI CKs = I CKs (x, y) - I CK(s-1) (x, y); CK

[0061] The environmental temperature change amount ΔT of the reference channel within the time period SJ is calculated through the formula ΔT s = T s -T s-1 s ; wherein s = 1, 2,..., S; S represents the total number of data collection times within SJ;

[0062] It is judged whether the absolute value of the light intensity distribution change amount is greater than a light intensity change threshold value; the light intensity change threshold value is set according to experience;

[0063] ​​is, when the absolute value of the environmental temperature change amount is greater than the temperature change threshold, no operation is performed; otherwise, a reference channel fault alarm signal is generated; the temperature change threshold is set according to experience;

[0064] No, no operation is performed.

[0065] The embodiment compares the change of the speckle pattern in the reference channel with the environmental temperature, and when the environmental temperature does not change much and the speckle pattern changes greatly, the reference channel may have a fiber fault problem at this time, and a warning operation is performed, which can ensure the normal operation and measurement accuracy of the fiber speckle displacement sensor.

[0066] In the embodiment, a wide-bandwidth fiber laser is used for laser generation; in another embodiment, a narrow-bandwidth fiber laser and a visible semiconductor laser can be used to replace the wide-bandwidth fiber laser to further increase the sensing sensitivity.

[0067] Some data in the above formula are calculated by removing the dimension, the formula is obtained by software simulation of a large amount of collected data to obtain a formula closest to the real situation; the preset parameters and the preset threshold in the formula are set by the person skilled in the art according to the actual situation or obtained by a large amount of data simulation.

[0068] The working principle of the present application is: obtaining the environmental temperature, displacement data and speckle data; obtaining a plurality of speckle data under a standard environmental temperature T; generating a speckle change amount according to the environmental temperature and the speckle data of the reference channel; generating measurement speckle data of the measurement channel according to the speckle change amount and the speckle data of the measurement channel; generating a displacement amount according to the measurement speckle data; generating an alarm signal according to the speckle data; making a prompt according to the alarm signal and contacting the management personnel; designing the reference channel to monitor the change of the speckle pattern caused by the environmental temperature, updating the speckle pattern of the sensor through the change of the speckle pattern of the reference channel, avoiding the decrease of the measurement accuracy of the sensor caused by the change of the environmental temperature, and making the application range of the fiber speckle displacement sensor wider, avoiding the problem that the existing technology often cannot effectively distinguish the speckle change caused by displacement and temperature, and limiting the application of the fiber speckle displacement sensor in high-temperature difference environments.

[0069] The above embodiments are only used to illustrate the technical method of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical method of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical method of the present application.

Claims

1. A temperature-compensated fiber-optic speckle displacement sensor, characterized by, The system comprises a data acquisition device, a data analysis device, a warning device and a data storage device. The data acquisition device acquires environmental temperature, displacement data and speckle data through a data acquisition device. The data analysis device acquires a plurality of speckle data under a standard environmental temperature T, generates a speckle change amount according to the environmental temperature and the speckle data of a reference channel, generates measurement speckle data of a measurement channel according to the speckle change amount and the speckle data of the measurement channel, and generates a displacement amount according to the measurement speckle data. An alarm signal is generated according to the speckle data. The warning device gives a prompt according to the alarm signal and contacts a manager. The speckle change amount is generated according to the environmental temperature and the speckle data of the reference channel, comprising: The measurement speckle data of the measurement channel is generated according to the speckle change amount and the speckle data of the measurement channel, comprising: Real-time acquisition of the environmental temperature T of the reference channel and the light intensity distribution of the speckle pattern in the corresponding speckle data and the standard environmental temperature BT and the light intensity distribution of the speckle pattern in the corresponding speckle data ; The amount of speckle variation in the reference channel is calculated by the formula ;​ The alarm signal is generated according to the speckle data, comprising: Obtaining a speckle variation of a reference channel and measuring a light intensity distribution of a speckle pattern in the speckle data of the measurement channel at ambient temperature T ; The light intensity distribution of the speckle pattern in the measurement channel at standard ambient temperature is calculated by the formula ;​ determining whether the absolute value of the light intensity distribution change amount is greater than a light intensity change threshold value; Acquire the environmental temperature T of the reference channel several times in the time period SJ and the light intensity distribution of the speckle pattern in the corresponding speckle data ; The amount of change in the light intensity distribution of the speckle pattern of the reference channel in the time period SJ is calculated by the formula ;​ The reference channel is calculated by the formula The amount of change in the ambient temperature of the reference channel in the time period SJ is calculated ; wherein s = 1, 2, …, S; S represents the total number of times of collecting data within SJ. if the absolute value of the environmental temperature change amount is greater than a temperature change threshold value, no operation is performed; otherwise, a reference channel failure alarm signal is generated; if not, no operation is performed. The displacement amount is generated according to the measurement speckle data, comprising:

2. The temperature-compensated optical fiber speckle displacement sensor according to claim 1, wherein acquiring the light intensity distribution of a speckle pattern in the measurement speckle data; inputting the light intensity distribution into a displacement calibration model to obtain the displacement amount; the displacement calibration model is constructed by an artificial intelligence model. The displacement calibration model is constructed by an artificial intelligence model, comprising:

3. The temperature-compensated optical fiber speckle displacement sensor according to claim 2, wherein acquiring a plurality of historical light intensity distributions and their corresponding displacement amounts; dividing the plurality of historical light intensity distributions and their corresponding displacement amounts into training data, verification data and test data; data preprocessing is performed on the training data, the verification data and the test data to obtain a training set, a verification set and a test set; selecting an artificial intelligence model as a base model; training the base model through the training set and adjusting the learning rate and the hyperparameters on the verification set to obtain a pre-trained model; the pre-trained model is verified on the test set, and finally a displacement calibration model with input of light intensity distribution and output of displacement amount is obtained. ​

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