Laser output temperature monitoring system based on optical fiber sensing and laser

Abstract

The invention belongs to the technical field of laser temperature detection, and discloses a laser output temperature monitoring system based on optical fiber sensing and a laser. An optical fiber temperature sensing unit is directly embedded in glue of a plugging member, and then optical fiber transmission is carried out, so that an all-optical sensing structure can be constructed; the temperature signal is directly transmitted to the optical fiber temperature sensing element through the glue, the response time is shortened to be within 50ms, the real-time performance of temperature monitoring is improved, and the optical transmission optical fiber can be beneficial to reducing the diameter and the weight of the wire harness and reducing the cost.

Description

Technical Field

[0001] This invention belongs to the field of laser temperature detection technology, specifically relating to a laser output temperature monitoring system and laser based on fiber optic sensing. Background Technology

[0002] When processing highly reflective materials such as copper and aluminum with high-power fiber lasers, the intense reflected light will be transmitted back into the QBH output head and focused inside it, generating a large amount of heat. This causes the temperature of the glue used to fix the output fiber to rise sharply, posing a risk of carbonization and burnout. This can lead to the failure of the entire laser output head or even damage to the core components inside the laser. Therefore, in high-power, high-reflectivity processing applications, it is crucial to monitor the temperature of the QBH plug glue in real time.

[0003] Existing commercial QBH output head temperature monitoring solutions employ electrical temperature sensors. This solution embeds the electrical temperature sensor on the back of the plug adhesive fixing component, indirectly monitoring the plug adhesive temperature via metal conduction. The signal processing circuit board required by the sensor is integrated on the back of the plug, forming a unified "sensor-circuit board" structure. The temperature signal is transmitted via two electrical leads, which, along with the optical fiber transmitting the laser, are integrated into an armored cable tube. The specific wiring structure is as follows: the transmission optical fiber is first wrapped separately in a small-sized Teflon tube, then passed parallel to the two electrical leads into a large-sized Teflon tube, and finally nested entirely within the armored cable tube. The optical fiber at the tail end of the armored flange connects to the laser body, while the electrical leads are connected to the laser circuit control section to form a closed-loop control. When the detected plug temperature exceeds a preset threshold, the sensor feeds back the temperature information to the overall control module, triggering a laser output stop command, thereby preventing optical path burn-out accidents. The temperature sensing principle of this scheme is based on the conversion of metal thermal conduction and electrical signals. It utilizes the thermal conductivity of metal materials to transfer heat from the adhesive to the sensor's sensitive element, and the temperature signal is acquired and converted via a circuit board. Its core control logic relies on the real-time transmission and processing of electrical signals, and it has wide applications in high-power laser processing. However, this scheme also has the following drawbacks: 1. Significant Temperature Response Lag: Due to the use of indirect heat conduction via metal, heat must travel through the metal substrate of the adhesive fixing component to reach the sensor, resulting in a significant thermal resistance effect. Actual measurement data shows that the temperature response time of this structure is typically in the hundreds of milliseconds range. In instantaneous high-temperature scenarios involving the processing of highly reactive materials, this response delay can easily lead to delayed protective actions.

[0004] 2. Deteriorated heat dissipation performance: The circuit board integrated on the back of the plug not only increases the structural volume (usually increasing the plug diameter by more than 30%), but also generates additional heat during operation, forming a localized heat source. This heat source, combined with the heat generated by laser processing, leads to a reduction in heat dissipation efficiency in the plug area by approximately 20%-30%, exacerbating the risk of high-temperature aging of the adhesive.

[0005] 3. Complex and bulky armored cable structure: To avoid frictional damage between the electrical leads and optical fibers, a "double Teflon tube nesting" structure is required. This design increases the armored cable diameter by at least 40% and its weight by more than 50%, while significantly increasing the complexity of the assembly process. This results in a thicker outer diameter, increased weight, decreased flexibility, high manufacturing costs, and a risk of lead wire breakage and short circuits. Statistics show that the manufacturing time for this structure is 2-3 times that of the ordinary structure, and the probability of damage to the optical fiber coating is still relatively high.

[0006] 4. Sensitive to electromagnetic interference: Electrical sensors and leads are susceptible to interference in strong laser electromagnetic environments, which may lead to temperature signal distortion. In 10 kW-level laser processing scenarios, temperature measurement errors caused by electromagnetic interference can reach ±2 ℃, affecting control accuracy. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a laser output temperature monitoring system and laser based on fiber optic sensing, so as to solve the problems of obvious temperature response lag, easy deterioration of heat dissipation performance and sensitivity to electromagnetic interference in the existing laser output head temperature detection.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, a laser output temperature monitoring system based on fiber optic sensing is provided, including a laser output component and a temperature detection unit. The laser input end of the laser output component is provided with a blocking component, and the blocking component is provided with a fiber fixing cavity through which the laser fiber passes and is fixed by glue. The temperature detection unit includes an optical fiber temperature sensing element, an optical fiber for transmission, a photoelectric conversion module, and a sensing light source. The optical fiber temperature sensing element is embedded in the optical fiber fixing cavity and fixed by the adhesive. The optical fiber temperature sensing element is connected to the photoelectric transmission module and the sensing light source through the optical fiber for transmission.

[0009] In one possible implementation, the photoelectric transmission module and the sensing light source are located inside the laser unit, and the fiber optic temperature sensing element is connected to the laser via an optical fiber to connect with the photoelectric transmission module and the sensing light source.

[0010] In one possible implementation, the optical transmission fiber and the laser fiber are arranged in parallel within the outer layer of the bundle, and the outer sides of the optical transmission fiber and the laser fiber are jointly covered by a protective layer.

[0011] In a possible implementation, the protective layer is a Teflon tube, and the outer layer of the wire harness is a wire harness armored cable outer tube.

[0012] In possible implementations, the fiber optic temperature sensing element is any one of a fiber grating, a fluorescent fiber, and a fiber optic interferometer.

[0013] In one possible implementation, the surface of the optical fiber is subjected to plasma treatment to create a rough structure, and a coating layer is disposed on the outer side of the optical fiber. The coating layer is attached and fixed to the optical fiber through the rough structure.

[0014] In one possible implementation, the optical transmission fiber is connected to the photoelectric conversion module and the sensing light source respectively via an optical fiber circulator.

[0015] On the other hand, a laser is also provided, including a laser output temperature monitoring system based on fiber optic sensing as described in any of the above technical solutions. The laser output temperature monitoring system is used to monitor the temperature change caused by laser reflection into the laser output component when the laser is processing highly reflective materials.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The laser output temperature monitoring system and laser based on fiber optic sensing of the present invention, by directly embedding the fiber optic temperature sensing unit in the adhesive of the sealing component and transmitting it through the fiber optic cable, can construct a fully optical sensing structure. The temperature signal is directly transmitted to the fiber optic temperature sensing element through the adhesive, and the response time is shortened to less than 50ms, which improves the real-time performance of temperature monitoring. Furthermore, the optical fiber transmission can help reduce the diameter and weight of the cable bundle, thereby reducing costs.

[0017] Moreover, by placing the photoelectric transmission module and the sensing light source inside the laser unit, which is far away from the high-temperature laser output components, the excitation output head can become a passive, non-heating terminal, which improves safety, avoids the need for circuit boards, reduces the size of the plug, improves heat dissipation efficiency, and effectively slows down the aging rate of the adhesive.

[0018] At the same time, by using optical signals as a carrier, electromagnetic interference can be effectively avoided, ensuring the extreme stability and reliability of signals in complex industrial environments. Attached Figure Description

[0019] Figure 1 A three-dimensional view of the connection structure between the laser output component and the temperature detection unit in a laser output temperature monitoring system based on fiber optic sensing. Figure 2 This is a three-dimensional cross-sectional view of the laser output component and temperature detection unit of a laser output temperature monitoring system based on fiber optic sensing. Figure 3 for Figure 2 A magnified view of a portion of the image; Figure 4 This is a partial cross-sectional view of the laser output component and temperature detection unit of a laser output temperature monitoring system based on fiber optic sensing. Figure 5 This is a schematic diagram of the transmission principle of a laser output temperature monitoring system based on fiber optic sensing.

[0020] In the diagram: 1-Laser output component; 11-Sealing component; 111-Fiber optic fixing cavity; 12-Quartz end cap; 13-Adhesive; 2-Wire harness armored cable outer tube; 3-Optical transmission fiber; 4-Laser fiber; 5-Temperature sensing element; 6-Protective layer; 7-Laser unit; 8-Laser; 9-Fiber optic circulator; 10-Sensing light source; 100-Photoelectric conversion module. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0022] Please refer to Figure 1-5 As shown, an embodiment of this application provides a laser output temperature monitoring system based on fiber optic sensing, including a laser output component 1 and a temperature detection unit. The laser input end of the laser output component 1 is provided with a sealing member 11, and the sealing member 11 is provided with a fiber fixing cavity 111 through which a laser fiber 4 passes and is fixed by adhesive 13. The temperature detection unit includes a fiber optic temperature sensing element 5, an optical transmission fiber 3, a photoelectric conversion module 100, and a sensing light source 10. The fiber optic temperature sensing element 5 is embedded in the fiber fixing cavity 111 and fixed by the adhesive 13. The fiber optic temperature sensing element 5 is connected to the photoelectric transmission module and the sensing light source 10 through the optical transmission fiber 3.

[0023] The laser output assembly 1 mainly includes a laser output head, which has a quartz end cap 12 and a sealing component 11 at the output end. The sealing component 11 is used to seal the input end and has an optical fiber fixing cavity 111 for fixing the laser optical fiber 4 through it with adhesive. The temperature detection unit mainly includes an optical fiber temperature sensing element 5, an optical transmission optical fiber 3, a photoelectric conversion module 100, and a sensing light source 10. The optical fiber temperature sensing element 5 is a temperature-sensitive element that is sensitive to changes in optical parameters such as light intensity, wavelength, phase, or polarization state. The temperature signal can be directly transmitted to the optical fiber temperature sensing element 5 through the adhesive 13, which can shorten the response time and improve the real-time performance of temperature detection. The fiber optic temperature sensing element 5 transmits the triggered optical signal through the optical transmission fiber 3 to the photoelectric conversion module 100 and the sensing light source 10. The sensing light source 10 excites the fiber optic temperature sensing element 5, enabling it to acquire a temperature signal. This signal is then transmitted through the optical transmission fiber 3 and converted by the photoelectric conversion module 100 to obtain temperature data, thus achieving temperature detection. Since signal transmission requires only a single optical transmission fiber 3, the diameter and weight of the wiring harness can be reduced, lowering costs.

[0024] Through the above technical solution, the fiber optic temperature sensing unit is directly embedded in the adhesive 13 of the sealing component 11 and then transmitted through the optical fiber, which can construct a fully optical sensing structure. The temperature signal is directly transmitted to the fiber optic temperature sensing element 5 through the adhesive 13, and the response time is shortened to less than 50ms, which improves the real-time performance of temperature monitoring. In addition, the optical transmission fiber 3 can help reduce the diameter and weight of the wire bundle and reduce costs.

[0025] In one embodiment, the photoelectric transmission module and the sensing light source 10 are disposed within the laser unit 7, and the fiber optic temperature sensing element 5 is connected to the laser 8 via the optical transmission fiber 3 to connect with the photoelectric transmission module and the sensing light source 10.

[0026] By placing the photoelectric transmission module and the sensing light source 10 inside the laser unit 7, which is far away from the high temperature of the laser output component 1, the excitation output head can become a passive, non-heating terminal, which improves safety, avoids the setting of circuit boards, reduces the size of the plug, improves heat dissipation efficiency, and effectively slows down the aging speed of the adhesive 13.

[0027] To further protect the optical transmission fiber 3 and the laser fiber 4, the optical transmission fiber 3 and the laser fiber 4 are arranged in parallel within the outer layer of the wire bundle, and the outer sides of the optical transmission fiber 3 and the laser fiber 4 are jointly covered by a protective layer 6.

[0028] This approach not only protects the optical transmission fiber 3 and the laser fiber 4, but also helps to reduce the diameter of the wire bundle.

[0029] Preferably, the protective layer 6 is a Teflon tube, and the outer layer of the wire harness is the wire harness armored cable outer tube 2. The wire harness armored cable outer tube 2 serves as the outer shell of the cable harness, providing primary protection, while the Teflon tube provides corrosion resistance and other benefits, better protecting the two optical fibers.

[0030] In some embodiments, the fiber optic temperature sensing element 5 is any one of a fiber grating, a fluorescent fiber, and a fiber optic interferometer.

[0031] Among them, fiber Bragg gratings, as temperature sensors, can acquire and sense temperature signals through wavelength modulation principles. Their core lies in the characteristic of the Bragg wavelength (λ-B) changing with temperature, thereby achieving temperature-to-optical signal conversion. Fluorescent optical fibers use pulsed light sources (such as LEDs or lasers) to excite fluorescent substances (such as Cr³⁺). + Er³ + / Yb³ + Doping materials cause the fluorescent material to transition from the ground state to the excited state. The fluorescence lifetime released when the fluorescent material returns to the ground state is negatively correlated with temperature, which can be used for temperature detection. Fiber optic interferometers utilize the characteristic that temperature changes cause changes in the refractive index and length of the fiber, resulting in a shift in the phase of the light wave or a shift in the interference wavelength for temperature detection. Fiber optic interferometers can be FP fiber optic interferometers or Mach-Zehnder interferometers. It should be noted that all three types of fiber optic temperature sensing elements 5 can be embedded in the adhesive 13, and their temperature sensing technologies are existing technologies, which will not be elaborated further here.

[0032] To improve the anti-friction performance of the optical fiber 3, the surface of the optical fiber 3 is subjected to plasma treatment to create a rough structure, and a coating layer is provided on the outer side of the optical fiber 3. The coating layer is attached and fixed to the optical fiber 3 through the rough structure.

[0033] In the specific implementation process, the optical transmission fiber 3 is connected to the photoelectric conversion module 100 and the sensing light source 10 through the optical fiber circulator 9.

[0034] In the embodiments of this application, a laser is also provided, including a laser output temperature monitoring system based on fiber optic sensing as described in any of the technical solutions. The laser output temperature monitoring system is used to monitor the temperature change caused by laser reflection entering the laser output component 1 when the laser 8 processes highly reflective materials.

[0035] In summary, the fiber optic sensing-based laser output temperature monitoring system and laser 8 of this application have the following beneficial effects: 1. Direct Embedded Sensing Unit Design: Using fiber optic gratings (FBG), FP fiber interferometers, Mach-Zehnder interferometers, or fluorescent optical fibers as sensing elements, the sensing unit is directly embedded inside the plug adhesive 13. Compared to existing technologies, this eliminates the metal conduction stage, allowing the temperature signal to be directly transmitted to the sensing unit via adhesive 13, reducing the response time to less than 50ms and improving the real-time performance of temperature monitoring.

[0036] 2. All-Optical Signal Transmission Architecture: The light source and photoelectric conversion module 100 are integrated into the laser's overall control system 7, achieving signal transmission through only a single sensing fiber. The sensing fiber and the laser transmission fiber are arranged in parallel within a single Teflon tube, eliminating the two electrical leads found in existing solutions. The fiber surface is reinforced with a coating after plasma treatment, significantly improving its abrasion resistance. This structure reduces the armor cable diameter by 40%, weight by 50%, simplifies the assembly process to single-tube threading, and increases production efficiency by over 60%.

[0037] 3. Lightweight, Circuit Board-Free Design: The signal processing circuit board on the back of the plug is completely removed. Temperature-to-optical signal conversion is achieved by utilizing the temperature sensitivity (λ_B drifts linearly with temperature) of the fiber optic sensor's wavelength / intensity. Wavelength encoding technology eliminates the influence of light source power fluctuations, achieving a measurement accuracy of ±0.1℃. This design reduces the plug volume by 30%, eliminates the heat source from the circuit board, improves heat dissipation efficiency by over 25%, and effectively slows down the aging of adhesive 13.

[0038] 4. Anti-interference system optimization: Utilizing the inherent electromagnetic interference resistance of fiber optic sensors, stable measurements are maintained even under 10kW laser processing conditions. Physical isolation from the laser transmission channel prevents mutual interference. The overall electromagnetic compatibility level of the system reaches or exceeds Level 3 of the IEC 61000-4-3 standard.

[0039] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A laser output temperature monitoring system based on fiber optic sensing, characterized in that, It includes a laser output component (1) and a temperature detection unit. The laser input end of the laser output component (1) is provided with a sealing component (11). The sealing component (11) is provided with an optical fiber fixing cavity (111) through which the laser optical fiber (4) passes and is fixed by glue (13). The temperature detection unit includes an optical fiber temperature sensing element (5), an optical fiber transmission (3), a photoelectric conversion module (100), and a sensing light source (10). The optical fiber temperature sensing element (5) is embedded in the optical fiber fixing cavity (111) and fixed by the glue (13). The optical fiber temperature sensing element (5) is connected to the photoelectric transmission module and the sensing light source (10) through the optical fiber transmission (3).

2. The laser output temperature monitoring system based on fiber optic sensing as described in claim 1, characterized in that, The photoelectric transmission module and the sensing light source (10) are located inside the laser unit (7). The fiber temperature sensing element (5) is connected to the laser (8) through the optical transmission fiber (3) to connect with the photoelectric transmission module and the sensing light source (10).

3. The laser output temperature monitoring system based on fiber optic sensing as described in claim 2, characterized in that, The optical transmission fiber (3) and the laser fiber (4) are arranged in parallel inside the outer layer of the bundle, and the outer sides of the optical transmission fiber (3) and the laser fiber (4) are covered with a protective layer (6).

4. The laser output temperature monitoring system based on fiber optic sensing as described in claim 3, characterized in that, The protective layer (6) is a Teflon tube, and the outer layer of the wire harness is the outer tube (2) of the wire harness armor cable.

5. The laser output temperature monitoring system based on fiber optic sensing as described in claim 1, characterized in that, The fiber optic temperature sensing element (5) can be any one of a fiber grating, a fluorescent fiber, and a fiber optic interferometer.

6. The laser output temperature monitoring system based on fiber optic sensing as described in claim 1, characterized in that, The surface of the optical fiber (3) is subjected to plasma treatment to form a rough structure. A coating layer is provided on the outside of the optical fiber (3). The coating layer is attached and fixed to the optical fiber (3) through the rough structure.

7. The laser output temperature monitoring system based on fiber optic sensing as described in claim 1, characterized in that, The optical transmission fiber (3) is connected to the photoelectric conversion module (100) and the sensing light source (10) respectively through the fiber optic circulator (9).

8. A laser, characterized in that, Includes a laser output temperature monitoring system based on fiber optic sensing as described in any one of 1-7 above, wherein the laser output temperature monitoring system is used to monitor the temperature change caused by laser reflection from the laser (8) into the laser output component (1) during processing of highly reflective materials.

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