Profiling of micrometer-sized laser beams in restricted volumes.

We present a method for determining the three-dimensional intensity distribution of directed laser radiation with micrometer resolution in restricted volumes. Our method is based on the incoupling and guiding properties of optical fibers, with the current version requiring only a few hundred micrometers across the measuring volume. We characterize the performance of the method and experimentally demonstrate profiling of micrometer-sized laser beams. We discuss the limiting factors and routes toward a further increase of the resolution and beam profiling in even more restricted volumes. Finally, as an application example, we present profiling of laser beams inside a micro ion trap with integrated optical fibers.