Measuring dynamic strain of structures using a gold-deposited extrinsic Fabry Perot interferometer

Abstract

In this paper, we present a new type of extrinsic Fabry-Perot interferometer (EFPI) for measurement of dynamic strain. Gold was deposited on the second reflecting surface of the optical fibre in this sensor to increase its reflectivity. Thus, we have termed it a gold-deposited extrinsic Fabry-Perot interferometer (G-EFPI). If a gap between two reflecting surfaces increases, the loss of intensity of the light that passes through the gap increases, causing a subsequent decrease in the output intensity of the sensor. Conversely, if the gap decreases, the amount of loss decreases and the output intensity increases. Therefore, it is possible to determine the variation of the gap size by observing the output intensity of the sensor. Finally, the dynamic strain of a composite specimen was measured successfully using the G-EFPI.

A simple load sensor based on a bent single-mode-multimode-single-mode fiber structure

“…where n0 (x, y) is the refractive index of the straight fiber and Reff is the equivalent bent radius which can be expressed as follows [21]:…”

“…The measured spectral response from the SMS structure at different load values at D2 The measured spectral response from the SMS structure at different load values at D2 = 3 cm For a bent MMF, the refractive index distribution is no longer symmetric and must be defined by an equivalent refractive index distribution as follows[21]:…”

Lamb Wave Detection Using PZT and Fiber Optic Sensor

“…The mode changes could not be found by these differences in waveform amplitudes due to the mode and reflected angle. The other sensitive sensor to detect the Lamb wave is a G-EFPI (gold-deposited EFPI) [8].…”

Parametric Study of the Reflective Periodic Grating for In-Plane Displacement Measurement Using Optical Fibers

“…It is only related to light collecting efficiency. However, before developing the simulation, the loss amount, which is induced by the air gap s , is analyzed theoretically in order to obtain a more logical reflected light magnitude with regard to light collecting efficiency [ 19 – 22 ]. In this paper, the normalized reflectance neglecting interference term is of interest for a fixed s .…”