Measurements of the orbital geometric phase

Summary form only given. This paper presents measurements of the orbital geometric phase by interferometric technique. This study focuses on the phases and spaces of first and second order modes. These modes are expressed in terms of Hermite-Gauss and Laguerre-Gauss functions. For the case of transformations between first order modes the path could be followed geometrically on the orbital Poincare sphere. For all paths investigated in first and second order spaces the measurements of the magnitude and sign of the geometric phase are in excellent agreement with the theoretical predictions.