Comparative Study on Decay Ratios of Laser-induced Fluorescence between Asbestos and Building Materials

Ozu, Akira  ; Esaka, Fumitaka  ; Yasuda, Kenichiro   

Decay ratios of the laser-induced fluorescence emitted from five types of asbestos and six types of building materials in the broad wavelength region from 350 to 700 nm were investigated by using an ultraviolet laser pulse of 266 nm. Dependence of the decay ratios on the wavelength were compared, and evaluated in an attempt to numerically discriminate asbestos from the other building materials. It was observed that the decay ratios of each material were not constant over the wavelength region and varied in the wavelength over time. The fluorescence of asbestos and the building materials except for rock fiber at above 500 nm decayed faster than that at below 500 nm. The wavelength region from 405 to 420 nm was found optimum to identify types of asbestos and to discriminate asbestos from the building materials by comparing the decay ratio at the delay time of 10 ns after the incidence of laser pulse.