Manifestation of Berry’s phase in image-bearing optical beams

We show that optical image-bearing beams manifest a generalized version of Berry's phase. This topological phase results in a rotation, equal to Berry's phase (with an opposite sign), of an arbitrary input optical image. Our method of measuring this phase applies to coherent as well as incoherent illumination, and thus is demonstrated experimentally using an incandescent light bulb. Furthermore, this is one of a few cases where a phase property of an ensemble of ``particles'' is unique, regardless of their energies, momenta, and spins.