A method and apparatus are provided for guiding an optical beam progressing along an axis of transmission defined by an optical converter. The method includes the steps of disposing an optically transparent substrate in the axis of transmission of the optical converter with a predominant plane of the substrate disposed perpendicular to the axis of transmission and so that the optical beam passes directly through the substrate and disposing a plurality of refracting or reflecting elements around the axis of transmission within a body of the optically transparent substrate.