Temperature sensor based on fluorescent optical fiber

Abstract

The utility model provides a temperature sensor based on a fluorescent fiber. The temperature sensor comprises a master control box; the fluorescence excitation unit is arranged outside the main control box, comprises a fluorescence probe and an ultraviolet light source, and emits excitation light through the ultraviolet light source to excite a fluorescent material of the fluorescence probe to emit fluorescence; the optical signal transmission and detection unit sequentially comprises a multimode optical fiber penetrating through the main control box, an optical filter and a photoelectric conversion module along an optical path, the optical filter and the photoelectric conversion module are arranged in the main control box, an optical signal outlet of the multimode optical fiber directly faces an optical signal receiving position of the photoelectric conversion module, and the optical filter is detachably clamped between the multimode optical fiber and the photoelectric conversion module; an optical signal inlet end of the multimode optical fiber is connected with the fluorescent probe; and the control and processing unit is arranged in the main control box, comprises a single chip microcomputer module and is used for controlling the ultraviolet light source to be turned on and turned off and receiving and processing signals transmitted by the photoelectric conversion module. According to the utility model, the optical path structure is greatly simplified, the difficulty and cost of manufacturing and maintenance are greatly reduced, and data processing is simplified.

Description

Technical Field

[0001] This utility model relates to an optical fiber sensing technology, and more specifically, to a temperature sensor based on fluorescent optical fiber. Background Technology

[0002] To ensure the safe operation of industrial equipment, especially in environments with high temperature, high pressure, strong electromagnetic fields, and high humidity, temperature monitoring is necessary. Common monitoring methods include manual inspection, infrared thermometry, thermocouple and resistance temperature detector (RTD) monitoring, and monitoring using fiber optic temperature sensors.

[0003] Currently, the most commonly used fiber optic temperature sensors are those based on fluorescence lifetime. Although these sensors have high measurement accuracy, their optical structure is complex, their manufacturing cost is high, their data processing is complicated, and their complex structure also increases maintenance costs. Utility Model Content

[0004] To address the aforementioned technical problems, this invention proposes a temperature sensor based on fluorescent optical fiber, which greatly simplifies the optical path structure, significantly reduces the difficulty and cost of manufacturing and maintenance, and facilitates simplified data processing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A temperature sensor based on fluorescent optical fiber, comprising:

[0007] The main control box is a hollow, sealable enclosure.

[0008] The fluorescence excitation unit, located outside the main control box, includes a fluorescence probe and an ultraviolet light source. The ultraviolet light source emits excitation light to excite the fluorescent material on the fluorescence probe to emit fluorescence.

[0009] The optical signal transmission and detection unit includes, in sequence along the optical path, a multimode optical fiber passing through the main control box, as well as a filter and a photoelectric conversion module built into the main control box. The optical signal outlet of the multimode optical fiber is directly opposite the optical signal receiving position of the photoelectric conversion module. The filter is detachably clamped between the two. The optical signal inlet end of the multimode optical fiber is connected to a fluorescence probe.

[0010] The control and processing unit, built into the main control box, includes a microcontroller module. The photoelectric conversion module and the ultraviolet light source are respectively connected to and controlled by the microcontroller module. The microcontroller module controls the opening and closing of the ultraviolet light source, as well as the reception and processing of signals transmitted by the photoelectric conversion module.

[0011] The structural features of this utility model also lie in:

[0012] The ultraviolet light source emits ultraviolet light with a wavelength of 385nm. The fluorescent material in the fluorescent probe emits blue fluorescence with a wavelength of 400-600nm when excited by ultraviolet light. The filter is a high-pass filter used to filter out light with wavelengths below 400nm.

[0013] The ultraviolet light source is an LED light source of model NSHU590B.

[0014] The photoelectric conversion module is a light intensity sensor, model GY-302BH1750FVI.

[0015] The microcontroller module is an Arduino microcontroller, model ATmega328P.

[0016] The main control box is divided into three independent areas by at least two partitions: a light source compartment, a sensor compartment, and a control compartment. The light source compartment and the sensor compartment are separated by a first partition with vertical slots. The filters are detachably inserted into the vertical slots and exposed through the through holes reserved on the first partition. They face the ground to the optical signal outlet of the multimode fiber and the optical signal receiving position of the photoelectric conversion module, respectively. The optical signal outlet side of the multimode fiber extends into the light source compartment, and the optical signal inlet end is exposed outside the main control box and connected to the fluorescence probe. The photoelectric conversion module is located in the sensor compartment, and the control and processing unit is built into the control compartment.

[0017] Compared with existing technologies, the beneficial effects of this utility model are reflected in:

[0018] This invention utilizes an external ultraviolet light source to excite the fluorescent material in the fluorescent probe to emit fluorescence. The fluorescence is transmitted via multimode fiber, and the optical signal is received and converted into an electrical signal by a photoelectric conversion module, which then feeds it back to the microcontroller module. This simplifies the complex optical path structure of existing sensors. Only a filter needs to be placed between the optical signal outlet of the multimode fiber and the optical signal receiving position of the photoelectric conversion module to filter out most of the ultraviolet light. This reduces the manufacturing and maintenance costs and difficulty of the sensor, and also simplifies data processing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] In the picture:

[0021] 1. Main control box; 11. First partition; 12. Second partition;

[0022] 21. Fluorescence probe; 22. Ultraviolet light source;

[0023] 31 Multimode optical fiber; 32 Optical filter; 33 Photoelectric conversion module;

[0024] 41 Microcontroller module; 42 Control board. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] Please refer to Figure 1 The temperature sensor based on fluorescent optical fiber in this embodiment includes:

[0027] The main control box 1 is a hollow, encapsulated box.

[0028] The fluorescence excitation unit is located outside the main control box 1 and includes a fluorescence probe 21 and an ultraviolet light source 22. The ultraviolet light source 22 emits excitation light to excite the fluorescent material on the fluorescence probe 21 to emit fluorescence. The fluorescence probe 21 faces the ultraviolet light source 22 with a gap between them and no obstruction.

[0029] The optical signal transmission and detection unit includes, in sequence along the optical path, a multimode optical fiber 31 passing through the main control box 1, a filter 32 and a photoelectric conversion module 33 built into the main control box 1. The optical signal outlet of the multimode optical fiber 31 is directly opposite the optical signal receiving position of the photoelectric conversion module 33. The filter 32 is detachably clamped between the two. The optical signal inlet end of the multimode optical fiber 31 is connected to the fluorescence probe 21.

[0030] The control and processing unit, built into the main control box 1, includes a microcontroller module 41, a photoelectric conversion module 33, and an ultraviolet light source 22, which are respectively connected to and controlled by the microcontroller module 41. The microcontroller module 41 controls the opening and closing of the ultraviolet light source 22, as well as the reception and processing of signals transmitted by the photoelectric conversion module 33.

[0031] In specific implementation, the corresponding structural configuration of the aforementioned temperature sensor also includes:

[0032] The ultraviolet light source 22 emits ultraviolet light with a wavelength of 385nm. The fluorescent material in the fluorescent probe 21 emits blue fluorescence with a wavelength of 400-600nm under the excitation of ultraviolet light. The filter 32 is a high-pass filter 32, which is used to filter out light with wavelengths below 400nm.

[0033] An optical fiber is installed so that the ultraviolet light generated by the ultraviolet light source 22 can be transmitted to the fluorescence probe 21 through the optical fiber.

[0034] The ultraviolet light source 22 uses an LED light source of model NSHU590B, whose relevant parameters include: wavelength 385nm, optical power 10mW, full width at half maximum (FWHM) 10nm, and drive current 50mA.

[0035] The fluorescence probe 21 has a quartz glass tube filled with BAM blue powder and epoxy resin. The mixing ratio of BAM blue powder to epoxy resin is 1:3. The BAM blue powder is BaMgAl. 10 O 17 Eu 2+ As a fluorescent material, it exhibits a temperature sensitivity of 0.8 Lux / ℃ (30-70℃), and the epoxy resin used is EPO-TEK OG116-31. The encapsulation process for fluorescent materials can be found at:

[0036] Step 1: Mix BAM blue powder (5μm particle size) with epoxy resin at a ratio of 1:3;

[0037] Step 2: After vacuum degassing, inject into a quartz glass tube. Curing conditions: bake at 80℃ for 2 hours.

[0038] Step 3: After packaging, perform an aging test (85℃ / 85%RH, 48 hours) to ensure stability.

[0039] The quartz glass tube serves as the main body of the fluorescence probe 21. It is made of high-purity fused silica with a light transmittance greater than 90% and a light transmission wavelength range of 300-2000nm. The tube has an inner diameter of 2mm, a length of 20mm, and a wall thickness of 1mm. The tube can be wrapped with a 0.2mm thick PTFE insulation layer to reduce the influence of environmental heat conduction. The quartz glass tube can be installed on a stainless steel probe mount. The total length of the fluorescence probe 21 is 25mm.

[0040] The photoelectric conversion module 33 is a light intensity sensor, model GY-302BH1750FVI, used to convert the received light signal into an electrical signal and transmit it to the microcontroller module 41. Relevant parameters include: measurement range 1-65535 Lux, resolution 0.83 Lux, I... 2 C communication rate 400kHz.

[0041] The microcontroller module 41 uses an Arduino microcontroller, specifically an ATmega328P, 16MHz. Its related electronic control design includes:

[0042] ① Constant current drive circuit:

[0043] Core chip: LM317T;

[0044] Parameters: Output current 50mA±0.5mA, ripple <5mV, efficiency >85%;

[0045] ②Signal conditioning circuit:

[0046] Core chip: AD620AN;

[0047] Parameters: Gain 100x, input noise 0.3μV√Hz, common-mode rejection ratio (CMRR) > 100dB;

[0048] ③ Power Management:

[0049] Input: 3.7V lithium polymer battery (2000mAh);

[0050] Boost converter chip: TPS61090 (output 5V / 1A, efficiency >92%);

[0051] Communication interface: Dual-mode communication between USB to serial port (CH340G) and Wi-Fi module (ESP8266), supporting local display and remote monitoring.

[0052] The control and processing unit also includes a control board 42, which is connected to the microcontroller module 41 for uploading real-time temperature data monitored by the sensor to the Internet of Things cloud platform for users to view.

[0053] Based on this embodiment, those skilled in the art can further develop and optimize the performance of the sensor. For example, if a temperature calculation algorithm is built into the microcontroller and a quantitative relationship between fluorescence intensity and temperature is established through experimental calibration, the temperature can be directly inverted through the light intensity by utilizing the correlation between the temperature and light intensity of the fluorescent material. Unlike fiber optic temperature sensors based on fluorescence lifetime, which require high-speed time measurement equipment to measure fluorescence lifetime, this greatly simplifies the internal structure of the fiber optic temperature sensor and reduces the manufacturing cost of the sensor.

[0054] The inner wall of the main control box 1 can be lined with copper foil with a thickness of 0.1mm for electromagnetic shielding. The box is divided into a light source compartment, a sensor compartment, and a control compartment by a first partition 11 and a second partition 12, both 2mm thick. A filter is detachably mounted on the first partition 11 between the light source compartment and the sensor compartment. The filter can be inserted from top to bottom into a pre-reserved slot on the first partition 11. The first partition 11 has pre-reserved through holes for the filter, allowing it to be exposed. A multimode optical fiber 31 is located on the side where the light source compartment is located, a photoelectric conversion module 33 is located in the sensor compartment, and a control and processing unit is located in the control compartment.

[0055] Taking temperature monitoring of the thyristor in the excitation system as an example, the working mode of the temperature sensor in this embodiment can be referred to as follows:

[0056] The first step is to bring the fluorescence probe 21 close to the silicon controlled rectifier (SCR). The microcontroller module 41 outputs a PWM signal (frequency 1Hz, duty cycle 50%) to drive the external ultraviolet light source 22 to emit light for 50ms. The excitation light is transmitted to the fluorescence probe 21, which excites the BAM blue powder to emit blue fluorescence.

[0057] In the second step, blue fluorescence is emitted from the fluorescence probe 21 and transmitted to the multimode fiber 31. The optical signal is transmitted in the multimode fiber 31, filtered by the filter 32, and finally transmitted to the photoelectric conversion module 33.

[0058] The third step is that the photoelectric conversion module 33 converts the light signal into an electrical signal, and transmits the electrical signal to the microcontroller module 41 for data analysis to obtain temperature data.

[0059] Fourth, the temperature data is transmitted from the microcontroller module 41 to the control board module 42, which then uploads the data to the corresponding IoT platform. This completes the measurement and monitoring of the temperature data.

[0060] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A temperature sensor based on fluorescent optical fiber, characterized in that: include: The main control box is a hollow, sealable enclosure. The fluorescence excitation unit, located outside the main control box, includes a fluorescence probe and an ultraviolet light source. The ultraviolet light source emits excitation light to excite the fluorescent material on the fluorescence probe to emit fluorescence. The optical signal transmission and detection unit includes, in sequence along the optical path, a multimode optical fiber passing through the main control box, as well as a filter and a photoelectric conversion module built into the main control box. The optical signal outlet of the multimode optical fiber is directly opposite the optical signal receiving position of the photoelectric conversion module. The filter is detachably clamped between the two. The optical signal inlet end of the multimode optical fiber is connected to a fluorescence probe. The control and processing unit, built into the main control box, includes a microcontroller module. The photoelectric conversion module and the ultraviolet light source are respectively connected to and controlled by the microcontroller module. The microcontroller module controls the opening and closing of the ultraviolet light source, as well as the reception and processing of signals transmitted by the photoelectric conversion module.

2. The temperature sensor based on fluorescent optical fiber according to claim 1, characterized in that: The ultraviolet light source emits ultraviolet light with a wavelength of 385nm. The fluorescent material in the fluorescent probe emits blue fluorescence with a wavelength of 400-600nm when excited by ultraviolet light. The filter is a high-pass filter used to filter out light with wavelengths below 400nm.

3. The temperature sensor based on fluorescent optical fiber according to claim 1 or 2, characterized in that: The ultraviolet light source is an LED light source of model NSHU590B.

4. The temperature sensor based on fluorescent optical fiber according to claim 1, characterized in that: The photoelectric conversion module is a light intensity sensor, model GY-302BH1750FVI.

5. The temperature sensor based on fluorescent optical fiber according to claim 1, characterized in that: The microcontroller module is an Arduino microcontroller, model ATmega328P.

6. The temperature sensor based on fluorescent optical fiber according to claim 1, characterized in that: The main control box is divided into three independent areas by at least two partitions: a light source compartment, a sensor compartment, and a control compartment. The light source compartment and the sensor compartment are separated by a first partition with vertical slots. The filters are detachably inserted into the vertical slots and exposed through the through holes reserved on the first partition. They face the ground to the optical signal outlet of the multimode fiber and the optical signal receiving position of the photoelectric conversion module, respectively. The optical signal outlet side of the multimode fiber extends into the light source compartment, and the optical signal inlet end is exposed outside the main control box and connected to the fluorescence probe. The photoelectric conversion module is located in the sensor compartment, and the control and processing unit is built into the control compartment.

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