Abstract: A method, system and unit for determining alignment in a layered device such as a semiconductor device includes providing a first layer having detectable surface and subsurface material properties and positioning a patterned photoresist layer over the first layer, patterned photoresist layer having detectable surface and subsurface material properties. The layers are imaged with a FIRAT probe to detect the material properties, and the detectable material properties are compared for mapping an alignment of the compared detectable material properties. The first layer may be a substrate or have a previously processed layer formed thereon. A surface topography may be included over the substrate and an etchable layer formed over the substrate or first layer. The FIRAT probe may be a single tip probe or a dual tip probe.