Impulsive stimulated thermal scattering, also known as transient grating photoacoustics, is a purely optical, noncontacting method capable of characterizing the high-frequency acoustic behavior of surfaces, thin membranes, coatings, and multilayer assemblies. It has emerged as a generally useful analytical technique for thin-film materials research. Recent advances in experimental design have improved and simplified the ISTS measurement dramatically, resulting in straightforward, inexpensive setups and even a commercial ISTS instrument that requires no user adjustments of lasers or optics. This tool is now used routinely in the microelectronics industry for rapid (~1 s) and nondestructive measurements of metal film thickness with atomic-level precision and high spatial resolution.