Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China
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Fluorescent Fiber Optic Temperature Sensors
The luminescent properties of certain fluorescent materials have a significant function of temperature, and the temperature can be obtained by measuring and calculating changes in the intensity, specific intensity, lifetime, and other characteristics of the material’s fluorescence. Fluorescent temperature sensors often also have optical waveguide components to propagate the excitation light from the light source and the fluorescence signal from the fluorescent material. Photonic crystal fiber optic fluorescence temperature sensors and measurement systems propagate the excitation and signal light through either the same or different optical paths. Specifically in the temperature sensor utilizing the same optical waveguide to propagate the excitation light and the signal light, the fluorescent material stored in a recessed portion of a cover is bonded to an end face of the optical waveguide, and the temperature probe is closed with a protective sleeve. The protective sleeve is attached to the housing in which the fluorescent material is stored. Previous fluorescent temperature sensors used the same optical waveguide to propagate the excitation light and the signal light with low signal strength, thus affecting the measurement accuracy. The additional mass of the thermal zone is large and the response of the probe to rapidly changing temperatures has a hysteresis; thermally induced perturbations in the protective cover change the temperature of the measurement point, making the sensor unable to measure the ambient temperature of the microzone.
Fiber Optic Fluorescence Temperature Sensors
Sensor probe structure is compact and small, high utilization rate of excitation light, signal stability, compatible with the fluorescence intensity method of measurement, and to avoid the fluctuation of excitation light intensity on the measurement of the impact of accuracy. Including spectral measurement module, control and signal processing module, photoelectric diode, light source, fiber optic beam splitter, sensor probe, which is characterized by the spectral measurement module connected to the control and signal processing module, control and signal processing module are connected to the photoelectric diode and light source, light source connected to the fiber optic light beam splitter, fiber optic light beam splitter are connected to the photoelectric diode and sensor probe. The light source is modulated as pulsed light or filtered excitation light source. Sensor probe including excitation light transmission fiber optic bundle, signal transmission fiber, constraint casing, fluorescent mixture, reflective layer, which is characterized by constraint casing fixed connection of six excitation light transmission fiber optic bundle and a signal transmission fiber, six excitation light transmission fiber optic bundle wrapped in a signal transmission fiber optic fiber bundle to form a fiber optic bundle, fiber optic bundle is connected to the end of the fluorescent mixture, the fluorescent mixture is connected to the periphery of the reflective layer. The fluorescent mixture is a cured product of mixing fluorescent material and liquid binder.
Characteristics of fiber optic sensors
Fiber optic sensors have many incomparable advantages of electrical sensors, such as immunity to electromagnetic fields and other changes in the external environment, high sensitivity, small size, good insulation, and distribution measurement, and so on, and therefore have been increasingly valued. Many physical quantities such as temperature, strain, displacement, humidity, pressure, sound, vibration, etc. can be measured with high precision using fiber optic sensors. Fiber optic sensing has been widely used in construction, petroleum, chemical, transportation, energy, metallurgy, medicine, military, avian products, nuclear industry and other fields. According to its working principle, fiber optic sensors can be divided into intensity modulation type and wavelength coding type. As the name suggests, fiber optic sensors working in wavelength coding mode use the wavelength of light as the identification of the detected quantity, i.e., the change of the detected quantity will be converted into the change of the wavelength of light. The biggest advantage is that the information of the detected quantity does not change with the change of light intensity, i.e., the information of the detected quantity does not change depending on the length of the transmission optical fiber and the loss of the optical fiber link, which is very important for long-distance corrosion detection. In addition, fiber optic sensors with wavelength coding function can be connected to the same fiber optic link by wavelength multiplexing, thus realizing multi-point or distributed measurement. The disadvantage of wavelength-coded fiber optic sensors is that they require a device with wavelength demodulation to extract the detected quantity from the wavelength of the light, i.e., the wavelength of the light needs to be measured. Compared to intensity measurements, wavelength measurements are more complex and generally require spectral analysis. At present, there are a variety of methods and techniques to achieve wavelength-encoded fiber-optic temperature sensing, which is widely used in the use of fiber Bragg grating (referred to as FBG) technology, long-period fiber grating (referred to as LPG) technology, optical fiber F・P technology and optical fiber multi-mode interference (MMI) technology, and so on. The wavelengths of FBG and MMI temperature sensors made from standard communication fibers are about 1.5 mm and the temperature sensitivity is about 1.5 mm. The wavelength-temperature sensitivity of LPG as a temperature sensor depends on the order of the cladding modes utilized by the LPG in both magnitude and sign. Currently realized wavelength-temperature sensitivity in -140pm/°C to -340pm/°C, fiber optic temperature sensor wavelength Korean sensitivity is an important technical indicator, high wavelength-temperature sensitivity is not only conducive to improving the accuracy and resolution of the measurement, but also reduces the requirements of the wavelength demodulation system, which can reduce the entire temperature sensing system manufacturing costs.
Why Use Fluorescent Fiber for Temperature Measurement
In many special temperature measurement environment, the temperature measurement may encounter some difficulties, and fluorescent fiber optic sensors with its excellent insulation, anti-electromagnetic interference, small size, low transmission loss, corrosion resistance, easy to install and other characteristics are increasingly being valued. The basic principle is to use blue-violet light to stimulate the fluorescent medium to produce fluorescence, fluorescence life with the temperature increases and decreases, so by detecting the fluorescence of the life of the measurement of temperature can be achieved. At present, the fiber optic temperature measurement methods applied to cable joints, high-voltage switchgear switch contacts mainly include distributed fiber optic temperature sensors, quasi-distributed fiber optic grating temperature sensors and plastic fiber optic fluorescence temperature sensors, of which the first two are more expensive, especially for a small number of or scattered temperature measurement points, requires a large amount of investment, resulting in a lot of unnecessary waste, and there are also many inconveniences during the construction process. There are also many inconveniences in the construction process. Plastic fiber optic fluorescent temperature sensors, although the cost is low, easy to construct, but the high temperature resistance of plastic fiber is poor, the application is greatly restricted.
