In-situ three-dimensional shape rendering from strain values obtained through optical fiber sensors

US8970845B1 · kind B1 · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Hon Man Chan · Santa Clarita, US
• Allen R. Parker, Jr. · Lancaster, US

Key dates

• Filing date: Dec 16, 2013
• Grant date: Mar 3, 2015
• Expiry date: Dec 16, 2033

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B11/18
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and system for rendering the shape of a multi-core optical fiber or multi-fiber bundle in three-dimensional space in real time based on measured fiber strain data. Three optical fiber cores arc arranged in parallel at 120° intervals about a central axis. A series of longitudinally co-located strain sensor triplets, typically fiber Bragg gratings, are positioned along the length of each fiber at known intervals. A tunable laser interrogates the sensors to detect strain on the fiber cores. Software determines the strain magnitude (ΔL/L) for each fiber at a given triplet, but then applies beam theory to calculate curvature, beading angle and torsion of the fiber bundle, and from there it determines the shape of the fiber in s Cartesian coordinate system by solving a series of ordinary differential equations expanded from the Frenet-Serrat equations. This approach eliminates the need for computationally time-intensive curve-tilting and allows the three-dimensional shape of the optical fiber assembly to be displayed in real-time.