Optical fiber temperature sensor based on Sagnac structure and method

Abstract

The invention relates to the technical field of temperature sensors, and provides an optical fiber temperature sensor and method based on a Sagnac structure, the sensor comprises a laser and an optical fiber patch cord, the optical fiber patch cord is connected with a coupler, the sensor also comprises a power meter, and the other end of the coupler is connected with the laser and the power meter at the same time; it can be understood that the light intensity change is monitored by introducing the power meter, the cost of the sensor can be effectively reduced, meanwhile, the operation process is simplified, and the measurement efficiency is improved; the novel optical fiber temperature sensing technology is not only suitable for clinical human body temperature measurement, but also has potential application value in other fields, such as environmental monitoring, industrial automation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature sensors, and more specifically, to an optical fiber temperature sensor and method based on a Sagnac structure. Background Art

[0002] The Sagnac fiber optic temperature sensor is a fiber optic sensor that uses the principle of the Sagnac effect and is widely used in high-precision temperature measurement. It is based on the Sagnac effect, an optical phenomenon related to rotation, first discovered by French physicist Georges Sagnac in 1913. The effect states that when light in a fiber optic loop propagates in a circle, the path length of the light propagating clockwise and counterclockwise will differ due to rotation;

[0003] In the Sagnac effect, if the fiber sensor loop is in a rotating state, the time it takes for light to propagate in the clockwise and counterclockwise directions will be different. This time difference is called the Sagnac phase difference. For a fiber sensor, temperature changes can affect the physical properties of the fiber (such as the refractive index), thereby changing the performance of the Sagnac effect;

[0004] Traditional fiber optic Sagnac ring sensors usually use spectrometers as light detectors for experimental testing in order to detect phase differences or frequency shifts caused by the Sagnac effect. The measurement accuracy of these spectrometers is usually on the order of 0.01nm. Although this can meet the basic requirements for high-precision temperature sensing, it faces some challenges in practical applications. First, the high-precision testing of spectrometers requires very complex operating procedures. At the same time, the price of the equipment is generally high, which makes it difficult to popularize in some application scenarios that require large-scale deployment.

[0005] In the field of fiber optic sensing technology, especially for the design and optimization of Sagnac temperature sensors, near-infrared light has become a commonly used excitation light source due to its high resolution, low noise characteristics and excellent anti-interference ability. Optical signals in the near-infrared band can be transmitted through optical fibers without being easily affected by electromagnetic interference, which is particularly important for high-precision temperature monitoring, especially in complex industrial environments. Compared with visible light or mid-infrared bands, near-infrared light can achieve stable transmission under a variety of environmental conditions and can penetrate some opaque media, which gives it significant advantages in many applications.

[0006] However, to achieve accurate measurement of near-infrared bands with a resolution of 0.01nm, the required spectrometer usually has high technical requirements. Such high-resolution spectrometers are not only expensive, but also have complex operation procedures and require highly professional technicians to operate and maintain. These factors make traditional spectrometers face significant costs and technical difficulties in large-scale application and promotion.

[0007] To solve the above problems, this application proposes an optical fiber temperature sensor and method based on a Sagnac structure. Summary of the invention

[0008] The purpose of the present invention is to provide a fiber optic temperature sensor and method based on a Sagnac structure, which achieves the purpose of low cost and high precision by introducing a power meter to monitor the change of light intensity.

[0009] The object of the present invention can be achieved by the following technical solutions: A fiber optic temperature sensor based on a Sagnac structure, comprising a laser and a fiber optic jumper, the fiber optic jumper is connected with a coupler, and also comprises a power meter, the other end of the coupler is connected with the laser and the power meter at the same time;

[0010] In the above technical solution, the sensor uses the Sagnac interference principle to form a closed loop through the combination of laser and fiber jumper. The coupler couples the optical signal of the laser and power meter into the fiber jumper to achieve the transmission and detection of the optical signal. The power meter is used to measure the intensity of the optical signal output from the coupler, and reflects the temperature change by detecting the change of output power. This design simplifies the structure of the sensor and improves the stability and reliability of detection.

[0011] The coupler is connected to the optical fiber jumper at the output end, and the coupler input end is connected to the laser and the power meter respectively;

[0012] In the above technical solution, the coupler is connected to the fiber jumper at the output end, and the coupler input end is connected to the laser and power meter respectively. This design ensures the effective transmission and distribution of optical signals and improves the sensitivity and stability of the sensor; as a key component, the coupler can efficiently couple the optical signals of the laser and power meter into the fiber jumper, reducing the loss of optical signals.

[0013] The power meter is used to measure the intensity of the optical signal output from the coupler;

[0014] In the above technical solution, the power meter is used to measure the intensity of the optical signal output from the coupler. By detecting the change in output power, the change in temperature can be accurately reflected; this design enables the sensor to monitor temperature changes in real time, improving the detection accuracy and response speed.

[0015] The coupler is used to couple the optical signals of the laser and the power meter into the optical fiber jumper;

[0016] In the above technical solution, the coupler is used to couple the optical signals of the laser and the power meter into the optical fiber jumper; the design and use of the coupler ensures the effective transmission of the optical signal, reduces the loss of the optical signal, and improves the sensitivity and stability of the sensor.

[0017] The coupler and the optical fiber jumper are connected to the laser to form a closed loop;

[0018] In the above technical solution, the coupler and the optical fiber jumper are connected to the laser to form a closed loop. This design ensures the effective transmission of the optical signal in the loop, reduces the loss of the optical signal, and improves the sensitivity and stability of the sensor; the closed loop design enables the sensor to better cope with environmental changes and improves the reliability and stability of detection.

[0019] An optical fiber temperature sensing method based on a Sagnac structure, the method comprising the following steps:

[0020] S1. Using a laser with a light source as the light source, the light wave is split into two beams and propagates in opposite directions when passing through a closed optical loop. When the temperature of the temperature-sensitive area changes, both beams of light will experience interaction;

[0021] S2. According to the birefringence effect, the effects on the fast axis and the slow axis are inconsistent, which causes the refractive index of the two beams to change, and then produces an optical path difference and a phase difference. When the two beams of light reunite in the coupler, interference will occur;

[0022] S3. The connected power meter detects the output power value of the output terminal;

[0023] In the above technical solution, the method uses a laser with a light source as the light source. When the light wave passes through a closed optical loop, it is divided into two beams and propagates in opposite directions. When the temperature of the temperature-sensitive area changes, the two beams of light will experience interaction. According to the birefringence effect, the effects on the fast axis and the slow axis are inconsistent, resulting in changes in the refractive index of the two beams of light, and then generating optical path difference and phase difference. When the two beams of light reunite in the coupler, interference will occur. The connected power meter detects the output power value at the output end. This method can achieve high-precision temperature sensing and is suitable for a variety of application scenarios.

[0024] A laser with a wavelength of 1550nm is used as the light source, and the optical signal is split into two beams through a coupler;

[0025] In the above technical solution, a laser with a wavelength of 1550nm is used as a light source, and the optical signal is divided into two beams through a coupler; this design utilizes a laser with a specific wavelength, which can improve the sensitivity and stability of the sensor; the laser with a wavelength of 1550nm has a higher transmission efficiency in optical fiber communication and is suitable for long-distance transmission and high-precision detection.

[0026] In the range of 35-40℃, the interference power value changes linearly with the increase of temperature, which can achieve high-precision temperature sensing;

[0027] In the above technical solution, in the range of 35-40°C, the interference power value changes linearly with increasing temperature, which can achieve high-precision temperature sensing; this design enables the sensor to have higher sensitivity and stability within a specific temperature range, and is suitable for application scenarios that require high-precision temperature detection.

[0028] The power meter is used to detect the output power value of the output end, and perform high-speed data sampling and convert it into digital quantity through the data acquisition unit;

[0029] In the above technical solution, the power meter is used to detect the output power value at the output end, and performs high-speed data sampling and conversion into digital quantities through the data acquisition unit; this design improves the speed and accuracy of data processing, allowing the sensor to monitor temperature changes in real time and transmit data to the control system or display device.

[0030] The output power of the laser is 30-40mW, and the working environment temperature range is 0℃-40℃;

[0031] In the above technical solution, the output power of the laser is 30-40mW, and the working environment temperature range is 0℃-40℃. This design ensures the stability and reliability of the sensor under different environmental conditions; the output power of 30-40mW can provide sufficient optical signal strength and is suitable for a variety of application scenarios.

[0032] Beneficial effects of the present invention:

[0033] The present invention introduces a power meter to monitor light intensity changes, cleverly replacing the traditional spectrometer's method of observing wavelength drift, thereby achieving high-precision temperature measurement while having significant cost advantages. Traditional spectrometers rely on accurate measurement of wavelength changes to reflect temperature changes, but this method is not only expensive in equipment but also complicated in operation, limiting its promotion in certain application scenarios; the present invention uses a power meter to monitor light intensity changes, and uses the linear relationship between light intensity and temperature to measure temperature, which can obtain high-precision measurement results at a lower cost and a simpler operating process.

[0034] In the temperature range of 35°C to 40°C, the power meter's reading shows a good linear change trend with temperature, with high measurement accuracy and stability. This feature makes the technology particularly suitable for clinical human body temperature measurement, providing fast and accurate temperature readings to meet the medical and health field's demand for precise temperature monitoring. In addition, the use of a power meter for light intensity monitoring avoids the high cost and complexity of traditional spectrometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 It is a structural schematic diagram of the present invention;

[0037] Figure 2 It is a schematic diagram of light transmission of the present invention;

[0038] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0039] In the figure: 1. Laser; 2. Power meter; 3. Coupler; 4. Fiber optic patch cord. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] like Figure 1 - Figure 2 As shown:

[0042] This embodiment provides a fiber optic temperature sensor based on a Sagnac structure, including a laser 1 and a fiber optic jumper 4, the fiber optic jumper 4 is connected to a coupler 3, and also includes a power meter 2, the other end of the coupler 3 is connected to the laser 1 and the power meter 2 at the same time:

[0043] Specifically, the laser 1 provides a light source with a wavelength of 1550nm, an output power of 30-40mW, and an operating environment temperature range of 0℃-40℃; the optical fiber jumper 4 uses high birefringence optical fiber, such as polarization-maintaining optical fiber PMD optical fiber, to enhance the interference effect, and the power meter 2 is used to measure the optical signal intensity at the output end.

[0044] As an implementation mode of the present invention, the coupler 3 is connected to the optical fiber jumper 4 at the output end, and the input end of the coupler 3 is connected to the laser 1 and the power meter 2 respectively;

[0045] Specifically, the coupler 3 is used to couple the optical signals of the laser 1 and the power meter 2 into the optical fiber jumper 4 .

[0046] This embodiment also provides a fiber optic temperature sensing method based on a Sagnac structure, the method comprising the following steps:

[0047] S1. Using a laser with a light source as the light source, the light wave is split into two beams and propagates in opposite directions when passing through a closed optical loop. When the temperature of the temperature-sensitive area changes, both beams of light will experience interaction;

[0048] S2. According to the birefringence effect, the effects on the fast axis and the slow axis are inconsistent, which causes the refractive index of the two beams to change, and then produces an optical path difference and a phase difference. When the two beams of light reunite in the coupler, interference will occur;

[0049] S3. The connected power meter detects the output power value at the output end.

[0050] As an embodiment of the present invention, a laser with a wavelength of 1550 nm is used as a light source, and the optical signal is divided into two beams by a coupler;

[0051] Specifically, the optical signal emitted by the laser 1 is divided into two beams by the coupler 3 and propagates in the optical fiber jumper 4 in opposite directions.

[0052] As an embodiment of the present invention, in the range of 35-40°C, the interference power value changes linearly with the increase of temperature, and high-precision temperature sensing can be achieved;

[0053] Specifically, when the temperature of the temperature-sensitive area changes, the optical path difference and phase difference in the optical fiber jumper 4 change, resulting in interference when the two beams of light are reunited in the coupler 3 .

[0054] As an embodiment of the present invention, the power meter is used to detect the output power value of the output terminal, and perform high-speed data sampling and conversion into digital quantity through the data acquisition unit;

[0055] Specifically, the power meter 2 detects the output power value of the output end, performs high-speed data sampling through the data acquisition unit and converts it into a digital value.

[0056] It can be understood that the present invention can effectively reduce the cost of the sensor by introducing a power meter to monitor the change in light intensity, while simplifying the operation process and improving the measurement efficiency; this new fiber optic temperature sensing technology is not only suitable for clinical human body temperature measurement, but also has potential application value in other fields, such as environmental monitoring, industrial automation, etc.

[0057] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "around" and the like indicate orientation or positional relationship, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred components or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0058] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical fiber temperature sensor based on a Sagnac structure, comprising a laser and an optical fiber jumper, characterized in that: The optical fiber jumper is connected with a coupler and also includes a power meter. The other end of the coupler is connected to the laser and the power meter at the same time.

2. The optical fiber temperature sensor based on Sagnac structure according to claim 1, characterized in that: The coupler is connected to the optical fiber jumper at the output end, and the coupler input end is connected to the laser and the power meter respectively.

3. The optical fiber temperature sensor based on Sagnac structure according to claim 1, characterized in that: The power meter is used to measure the intensity of the optical signal output from the coupler.

4. The optical fiber temperature sensor based on Sagnac structure according to claim 1, characterized in that: The coupler is used to couple the optical signals of the laser and the power meter into the optical fiber jumper.

5. The optical fiber temperature sensor based on Sagnac structure according to claim 1, characterized in that: The coupler and the optical fiber jumper are connected with the laser to form a closed loop.

6. A fiber optic temperature sensing method based on a Sagnac structure according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1. Using a laser with a light source as the light source, the light wave is split into two beams and propagates in opposite directions when passing through a closed optical loop. When the temperature of the temperature-sensitive area changes, both beams of light will experience interaction; S2. According to the birefringence effect, the effects on the fast axis and the slow axis are inconsistent, which causes the refractive index of the two beams to change, and then produces an optical path difference and a phase difference. When the two beams of light reunite in the coupler, interference will occur; S3. The connected power meter detects the output power value at the output end.

7. The optical fiber temperature sensing method based on Sagnac structure according to claim 6, characterized in that: A laser with a wavelength of 1550nm is used as the light source, and the optical signal is split into two beams through a coupler.

8. The optical fiber temperature sensing method based on Sagnac structure according to claim 6, characterized in that: In the range of 35-40℃, the interference power value changes linearly with increasing temperature, which can achieve high-precision temperature sensing.

9. The optical fiber temperature sensing method based on Sagnac structure according to claim 6, characterized in that: The power meter is used to detect the output power value of the output end, and performs high-speed data sampling and conversion into digital quantity through a data acquisition unit.

10. The optical fiber temperature sensing method based on Sagnac structure according to claim 6, characterized in that: The output power of the laser is 30-40 mW, and the working environment temperature range is 0°C-40°C.

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