Spectroscopic Polymer Optical Fiber sensor for orbital arc-welding on-line monitoring

Abstract

Plasma optical spectroscopy has proved to be a promising solution for the on-line monitoring of both laser and arc-welding processes, where quality assurance plays a mayor role, especially in some particular industrial scenarios like aeronautics. Despite the robustness provided by these spectroscopic analysis techniques, the implementation of an efficient and non-invasive optical sensor system is not always feasible. Input optics based on optical collimators are commonly employed, but when complex shapes are to be welded, or specific welding processes are being considered, a different approach must be designed. In this paper we propose an optical sensor based on the use of a Polymer Optical Fiber (POF) as the input optics. The external protection of the POF is removed, providing an acquisition of the plasma radiation from the fiber cladding. Experimental welding tests will show the feasibility of the proposed POF sensor.