Refractive Index Description
The refractive index distribution can be specified in one of two ways:

An arbitrary refractive index profile can be uploaded as a
twocolum text file. The first column is the distance and the second column is the refractive index.
Click here for an example.

The refractive index can be created using a set of builtin linear functions. Each function
has the form f(y).
Multiple functions can be entered, and
most geometries of interest can be constructed this way. Click here for a complete description. The background index is assumed to be 1.0, and every function adds an
incremental value.