Beam shaping diffuser based fiber injection for increasing stability of industrial robotic laser applications

This paper documents the investigation of a diffuser based fiber injection system and its successful implementation and experimental testing in a robotic industrial process. This is a new concept based on the idea that a diffuser that has the angular radiation pattern matching the NA of the fiber can be used to approximate the field pattern at the face of a mode filled fiber. The research considered two approaches to this problem. The two related approaches to the problem were developed conceptually and analytically for two predominant wavelengths of interest, 1030 nm and 532 nm. The first is an implementation that would consist of illuminating the diffuser with a uniform spot having the same shape as the fiber core and imaging the illuminated spot onto the fiber face. The other approach is the use of a far-field (Fourier transform) diffractive element with a transform lens. This paper will provide an overview of the analytics and testing of the later concept (Fourier transform) and the experimental implementation of the design to a laser fiber coupling system to launch a 532 nm pulsed laser beam into a square core fiber optical beam delivery system. Further detail will be shared with the experimental performance of the design when integrated within a multi-axis robotic arm, which has six degrees of freedom. These results will include how the fiber injection system improved laser beam stability during process operations, in comparison to traditional simple lens injection methods.