Dynamic high-pressure calibration of the fiber-optic sensor based on birefringent side-hole fibers

Abstract

This paper presents a dynamic pressure calibration of the fiber-optic interferometric sensor based on highly birefringent side-hole fibers. Earlier, we tested other types of fiber-optic sensors based on the same principle for measurements of static and quasi-static pressure. To apply the sensor for measurements of fast pressure changes, the dynamic analysis is crucial due to the occurrence of resonance phenomena and due to the possibility of false pressure readings. We applied a static calibration procedure to initially determine the pressure sensitivity and temperature stability of the sensor. Next, we compared the characteristics of the fiber-optic sensor with the responses of a calibrated piezoelectric dynamic pressure sensor at an operating range of 110 bar with a sampling rate equal to 200 kHz. The characteristics of the fiber-optic sensor are in good agreement with those of the reference piezoelectric sensor for the linear and exponential functions and for the half-sine when the pulse is wider than 400 ms. However, for half-sine pulses narrower than 250 ms, resonance oscillations occur only in the reference sensor. Construction of the fiber-optic sensor reduces the undesirable oscillations, which thereby makes it possible to operate on frequencies higher by about one order than in the case of the piezoelectric sensor. It clearly shows that the highly birefringent fiber-optic sensors can be successfully applied for measurements of rapid pressure changes.