Depth profiling of optical absorption in thin films via the mirage effect and a new inverse scattering theory. Part II: Experimental reconstructions on well-characterized materials

Mirage effect spectrometry is experimentally evaluated in this work as a te chnique of optical depth profiling in thin films where no prior information is available about the sample properties. An apparatus suitable for perfor ming quantitative measurements is described. High-precision experimental al ignment procedures are introduced along with a new method for precise optic al correction of the detector signal for experimental frequency response no nuniformities. Reconstructions were made of the heat source density and abs orption coefficient depth profile in materials with known depth dependence. These included samples approximating weighted delta function arrays, and d epth-continuous media known to obey Beer's law to a good approximation. The properties of these samples were examined independently by using a techniq ue of depth-sensitive light microscopy. Mirage effect depth profiles recons tructed on samples containing discrete absorbers were effectively regulariz ation limited, indicating that resolution is limited by random error in the data rather than experimental bias. Depth profiles obtained in continuousl y absorbing media show a good agreement with those obtained by reference me thods.