Hsien-Chi+Yeh

A fiber-optic accelerometer based on the wavefront-splitting interferometry is described in this paper. Within a compact sensing space surrounded by two single-mode fibers and a flat specimen surface, two-beam interferences occur by superimposing radiations with split wavefronts caused by reflections on specimen surface. Due to a small divergence angle of Gaussian laser beam emitting from the single-mode light-emitting fiber, radiations traversing toward the specimen have an incident angle of nearly 90o, and consequently the reflection coefficient becomes relatively high for most of the materials with a flat surface. Using this sensing scheme, we designed a displacement-type accelerometer, shown in Figure 1. The stainless-steel proof-mass having a weight of 23.2 g is connected to a base by using an OHP transparency strip, in order to obtain a larger damping coefficient and hence a wider sensing spectrum range. The resonance frequency of proof mass was measured to be 12.5 Hz. In the preliminary experiments, the whole system was put on an optical table, and an ambient noise level of 5 nm was obtained, which is corresponding to an acceleration of 30 m g. Figure 1 showing the structure of fiber-optic accelerometer.
 * Fiber-optic accelerometer using the wavefront-splitting interferometry **ppt/pdf
 * Hsien-Chi Yeh, School of Engineering, Zhongshan University, Guangzhou **

Keywords: Accelerometer; Fiber optic sensors; Wavefront-splitting interferometer