A free electron laser (FEL) with its characteristics of wide wavelength tunability,ultrashort pulse time structure,and high peak power density is predominantly superior to all other conventional lasers in applications.Several experimental studies on mid-infrared FEL irradiation on dental enamel and dentine were performed at the Beijing FEL. EXperimental aims were to investigate changes in the hardness,ratios of P to Ca and Cs before and after irradiation on samples with a charateristic absorption wavelength of 9.66μm,in the colors of these sample surfaces after irradiation with different wavelengths around the peak wavelength.The time dependence of temperature of the dentine sample was measured with its ps pulse effects compared to that with a continuous CO2 laser.FTIR absorption spectra in the range of 2.5-15.4μm for samples of these hard dental substances and pure hydroxyapatite were first examined to decid their chemical components and absorption maximums.Primary experimental resulte will be presented.2001 Elsevier Science B.V.All rights reserved.
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