摘要:
Methods that include directing an incident beam towards a substrate, the substrate having one or more features formed thereon wherein the incident beam has a wavelength from about 10 μm to about 10 mm, and the incident beam interacts with the substrate to form a modulated beam; varying one or more characteristics of the incident beam while directed towards the substrate; detecting the modulated beam while varying the one or more characteristics of the incident beam to collect a spectrum; and determining at least one spatial metric of the at least one feature based on the collected spectrum.