  White light interferometry (WLI) can be used to obtain surface morphology
information on dimensional scale of millimeters with lateral resolution as good
as ~1 {\mu}m and depth resolution down to 1 nm. By performing true
three-dimensional imaging of sample surfaces, the WLI technique enables
accurate quantitative characterization of the geometry of surface features and
compares favorably to scanning electron and atomic force microscopies by
avoiding some of their drawbacks. In this paper, results of using the WLI
imaging technique to characterize the products of ion sputtering experiments
are reported. With a few figures, several example applications of the WLI
method are illustrated when used for (i) sputtering yield measurements and
time-to-depth conversion, (ii) optimizing ion beam current density profiles,
the shapes of sputtered craters, and multiple ion beam superposition and (iii)
quantitative characterization of surfaces processed with ions. In particular,
for sputter depth profiling experiments of 25Mg, 44Ca and 53Cr ion implants in
Si (implantation energy of 1 keV per nucleon), the depth calibration of the
measured depth profile curves determined by the WLI method appeared to be
self-consistent with TRIM simulations for such projectile-matrix systems. In
addition, high depth resolution of the WLI method is demonstrated for a case of
a Genesis solar wind Si collector surface processed by gas cluster ion beam: a
12.5 nm layer was removed from the processed surface, while the transition
length between the processed and untreated areas was 150 {\mu}m.
