Transient grating spectroscopy uses interfering lasers to evaluate surface properties (i.e. thermal properties and elastic properties) to a variable depth.
Notably, it can be used in in-situ measurements.
How does it work? Interference between two lasers creates periodic heating. We observe the decay of the grating and infer properties from that.
Mike Short et al. are working on a Portable transient grating spectroscopy device.