Two-dimensional index profiling of fibers and waveguides

We have constructed a two-dimensional refracted-ray scanner that can resolve index-of-refraction increments of approximately 4 x 10(-5). This resolution is an order of magnitude finer than the uncertainty of the measurement. The scanner can be adapted to evaluate either fibers or planar waveguides. The two-dimensional scan and the high precision allow visualization of features, such as deposition layers, that are difficult if not impossible to see in conventional one-dimensional scans.