title: Nonlinear scattering in hard tissue studied with ultrashort laser pulses.
abstract: The back-scattered spectrum of ultrashort laser pulses (800 nm, 0.2 ps) was studied in human dental and other hard tissues in vitro below the ablation threshold. Frequency doubled radiation (SHG), frequency tripled radiation and two-photon fluorescence were detected. The relative yield for these processes was measured for various pulse energies. The dependence of the SHG signal on probe thickness was determined in forward and back scattering geometry. SHG is sensitive to linear polarization of the incident laser radiation. SHG in human teeth was studied in vitro showing larger signals in dentin than in cementum and enamel. In carious areas no SHG signal could be detected. Possible applications of higher harmonic radiation for diagnostics and microscopy are discussed.
authors.affiliation: University of Applied Sciences, Technische Fachhochschule Berlin.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Eichler
authors.forename: Beop-Min
authors.initials: BM
authors.lastname: Kim
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000528:radiation effects; D002417:Cattle; D002645:Chickens; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging; D007834:Lasers; D019047:Phantoms, Imaging; D012542:Scattering, Radiation; D013552:Swine; D014070:Tooth / Q000000981:diagnostic imaging* / Q000528:radiation effects; D014463:Ultrasonography