Analysis of Fiber Optic Sensor Embedded in Metals by Automatic and Manual TIG Welding

Abstract

In this paper, the embedding of fiber optic sensors in metals, by using both automatic and manual tungsten inert gas welding (TIG) is discussed for nickel- and copper-coated fiber Bragg gratings (FBG) written into an optical fiber, as embedding such sensors in metals provides protection against environmental effects. In the investigation and analysis of the performance of a number of such sensors, copper-coated sensors were seen to lose their temperature and strain sensitivity while being embedded due to damage to the coating, while with a nickel coating the sensors in the fiber were found to withstand the process with a lesser effect on the sensor performance. The research has also shown that the automatic TIG process used is less invasive than the manual TIG approach, although more expensive to implement.