Scanning total reflection method for refractive-index profiling

A simple index-distribution measurement method using scanning total reflection (STR) is presented. On the basis of preliminary experiments, its accuracy confirmed to be 0.1% with a spatial resolution of 2 μm. Further considerations show that the theoretical limits of these values can be better than 0.01% and 1 μm, respectively. The results of rod lenses measured by the STR method and the interference method coincided, and measurement reproducibility was confirmed. The index profile of a planar microlens was measured and the result was found to coincide with a theoretically predicted result.