Optical Strain Gauge Prototype Based on a High Sensitivity Balloon-like Interferometer and Additive Manufacturing

Abstract

An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber’s curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/μϵ.

A century on diameter measurement techniques in cylindrical structures

“…Concerning the use of AM for the manufacturing of cylindrical layouts, it has been demonstrated that fiber optic sensing is well suited for diameter measurement of these structures. An example of this is reported by Cardoso et al [58][59][60]. The authors proposed and compared two sensing configurations, one based on a single FBG, another combining an FBG and a fiber taper.…”

“…The modal interference pattern shifts when displacement is applied to the interferometer as a result of measurand variations [75][76][77]. The detection of these shifts combined with proper modeling allows to obtain information about the changes [59,78,79].…”