High-precision and long-range optical fiber Fabry-Perot interferometer for high temperature measurement

To solve the problem of near-field measurement of aeroengines a novel large-range high-precision Fabry-Perot interferometer (FPI) is developed, which is verified by a high-temperature experiment. Based on the principle of FPI wavelength drift and frequency spectrum drift, a double-beam-interference FPI is designed. Through an analysis of the optical path difference between the two beams, the conclusion that the spectrum drifts to the long-wave direction with the increase of temperature is obtained. Moreover, through frequency spectrum analysis, the measurement error caused by the distortion of the spectrum is avoided, and it is found that the increase in temperature will cause the change in frequency spectrum. The temperature sensitivity of the glass-type FPI is only 0.0011 nm degrees C-1. A ceramic material with a higher thermal expansion coefficient is selected as the collimating tube to make the sensitivity of the temperature sensor as high as 0.691 nm degrees C-1 from normal temperature to 100 degrees C. To meet the needs of a wide range of measurements from room temperature to 1000 degrees C the frequency drift method is utilized. A field experiment is carried out on the ceramic FPI at the tail spray of the aeroengine simulation platform. The temperature response test from normal temperature to 1000 degrees C is completed, and the accuracy of the sensor reached 0.043%. In this study, the principle, design, production, and testing of optical fiber sensors are carried out. The developed optical fiber sensor has significance for high temperature monitoring.