Bc. Li et al., SEPARATION OF OPTICAL THIN-FILM AND SUBSTRATE ABSORPTION BY OBLIQUELY-CROSSED PHOTOTHERMAL DEFLECTION - THEORY, J. mod. opt., 42(5), 1995, pp. 1093-1107
An explicit three-dimensional calculation of c.w. modulated phototherm
al deflection (PTD) with obliquely crossed geometry, including optical
thin film and substrate absorption, has been presented. Theoretical r
esults show that the obliquely crossed PTD technique is feasible to se
parate the thin film and substrate absorption, and to measure low thin
film absorption under high substrate absorption by appropriately adju
sting the cross-point position of the excitation and probe beams. Meas
urement of the thin film absorption is not affected by the thermal pro
perties of the substrate. The obliquely crossed PTD also provides a me
thod for real-time monitoring of thin film generation.