FT-IR STEP-SCAN PHOTOACOUSTIC PHASE-ANALYSIS AND DEPTH PROFILING OF CALCIFIED TISSUE

Rapid-scan- and step-scan-based Fourier transform infrared photoacoust ic depth profiling results of an extracted but intact human tooth are compared. The effects of various data processing methods are examined. Analysis of the phase dispersion of the photothermal signal along wit h spectral linearization is used to access the extent of photoacoustic saturation in the photoacoustic spectra. Phase-modulated/phase-resolv ed depth profiling methods are less prone to photoacoustic saturation and provide superior localization of the surface and subsurface absorb ers distributed in the tooth enamel. Mid-infrared depth profiling stud ies of calcified tissues can aid in the understanding of degenerative bone diseases, bone growth, and modeling, as ''ell as tissue mineraliz ation.