Kaleidoscope modes in large aperture Porro prism resonators

We apply a new method of modeling Porro prism resonators, using the concept of rotating loss screens, to study stable and unstable Porro prism resonator. We show that the previously observed petal-like modal output is in fact only the lowest order mode, and reveal that a variety of kaleidoscope beam modes will be produced by these resonators when the intra-cavity apertures are sufficiently large to allow higher order modes to oscillate. We also show that only stable resonators will produce these modes. (C) 2008 Optical Society of America.