Comparative analysis of calibration methods for fiber Bragg grating temperature sensor used in asphalt pavement

Temperature sensitivity of fiber Bragg grating temperature sensor used in asphalt pavement is influenced by its testing medium. As a result, calibration test for this type of sensor is the prerequisite to capture absolute temperature of asphalt pavement accurately. At first, the wavelength drift of fiber Bragg grating temperature sensor in both water bath and asphalt concrete specimen was monitored, through which the relationship between reflection wavelength and temperature was established. Then, calibration equations of each sensor were carried out by linear fitting analysis of test data. Temperature sensing characteristics and its difference of the same sensor in water bath and asphalt concrete were compared and analyzed. Results show that temperature sensitivities in different media are different even for the same sensor. What's more, calibration based on asphalt concrete specimen environment is more consistent with the actual condition, which has a certain practical value.