Cómo utilizar fibra óptica fluorescente para medir el principio de temperatura

Principle of Fluorescence Lifetime Temperature Measurement

After being irradiated with light, the electrons in the sensitive material absorb photons and transition from low energy level to excited state high energy level, and then return to low energy level through radiation transition, emitiendo fluorescencia. The sustained fluorescence emission after the excitation light is eliminated depends on the lifetime of the excited state. This emission typically decays exponentially, and the time constant of exponential decay can be used to measure the lifetime of the excited state, which is called the fluorescence lifetime or fluorescence decay time.

Fluorescence lifetime temperature sensor

The length of fluorescence lifetime depends on the temperature. Fluorescence lifetime temperature sensors emit linear spectra in the visible spectrum after certain rare earth fluorescent substances are irradiated and excited by ultraviolet light, Es decir, fluorescence and its afterglow are the luminescence after the excitation stops. If a parameter of fluorescence is modulated by temperature and the relationship is monotonic, esta relación se puede utilizar para medir la temperatura. The intensity of the linear spectrum is related to the intensity of the excitation light source and the temperature of the fluorescent material. If the light source is constant, the intensity of the fluorescent linear spectrum is a single value function of temperature and decays over time. Generalmente, the lower the external temperature, the stronger the fluorescence and the slower the decay of afterglow. By filtering out the excitation spectrum through a filter and measuring the intensity of the fluorescence afterglow emission spectral lines, la temperatura se puede determinar. But this measurement method requires stable excitation light intensity and signal channel, which is difficult to achieve, so it is rarely used. Además, the decay time constant of fluorescence afterglow is also a single value function of temperature.

From the perspective of semiconductor theory, the decay and disappearance of afterglow is the quenching process of light. Cuanto mayor sea la temperatura, the stronger the lattice vibration, the more phonons participate in absorption, and the faster the light quenching. Por lo tanto, the temperature of fluorescent materials determines the speed of light quenching, Es decir, the size of the decay time constant.

The biggest advantage of using fluorescence lifetime for temperature measurement is that the temperature conversion relationship is determined by the fluorescence lifetime, and is not affected by other external factors such as changes in excitation light source intensity, fiber transmission efficiency, or coupling degree. Por lo tanto, it has significant advantages over the temperature measurement method using fluorescence peak intensity or intensity ratio as the temperature sensing signal, and is based on the principle of fiber optic temperature measurement.

Sensor de temperatura de fibra óptica, Sistema de monitoreo inteligente, Fabricante de fibra óptica distribuida en China