A white-light interferometric extrinsic Fabry-Perot strain sensor that uses a multimode fiber is demonstrated. The Fabry-Perot cavity length is measured with the help of a Fizeau interferometer. The sensor is described, and some results obtained at this time are given. The strain measurements are absolute and perfectly linear, with a sensitivity of 0.25 micrometers per meter (micro). the design of a thermally autocompensated strain sensor is also presented.
The reflectance vs angle of incidence method was used to determine the refractive index and absorption coefficient of dental enamel at CO(2) laser wavelengths. A strong wavelength dependence of the optical constants was observed in this spectral region which corresponds to a well-known absorption band of hydroxyapatite, the main constitutent of dental enamel. A directional dependence of the optical constants of dental enamel was also observed. The absorption coefficient reaches a maximum between 9.75 and 10 microm. This particularity may be important for the main CO(2) laser treatments proposed in dentistry up to now: surface treatment of teeth and fusion of dental materials.
Several types of small-dimension graded-reflectance mirrors deposited through rotating masks are compared. Multilayer mirrors provided with single-variable-thickness layers have limitations that are avoided when all the layers in the system are shaped. High-reflectance mirrors of the latter type are demonstrated. Numerical and experimental results are given.
The use of lasers to ablate atherosclerotic plaque has proved promising. To achieve safe conditions of laser angioplasty, researchers have proposed different methods for accurate localization of plaque. Research has been done on the use of induced fluorescence in distinguishing normal arteries from affected ones. In the present study, an entire fluorescence spectrum (excitation–emission) from 200 to 1000 nm has been done on normal and affected arteries. Previous studies on the fluorescence spectroscopy of arterial walls have generally been done at discrete excitation wavelengths. Our study shows that the entire fluorescence spectrum gives a more accurate diagnosis.
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