Measurement &Evaluation of Scattered Laser beam and Reflectivity of Some Surfaces as a Means of Laser Safety

Abstract

Abstract In this study linear and angular scattered intensity of different samples were measured also the reflectivity of samples as a mean of safety was determined. Samples were chosen according to the, availability and uses in laser clinics and laboratories. Samples under study were Aluminum with different coatings, glass, and ceramic. Two types of lasers were used as a source of irradiation; He-Ne laser (λ = 632.8nm, P = 1mW), Diode laser (λ = 808nm, P = 500mW). The detection systems used were: photomultiplier for the former and I.R detector for the later. The reflectivity of samples was determined for different materials at different incident angle (10°, 20°, 30°) The values of linear scattered intensity was measured at scattering angle (10°), and the distance between detector and samples had been changed, this shows inverse relation due to the interaction of the scattered beam with air molecules. In angular scattering the measurement was achieved using a chamber in two situations, before and after covering the chamber. The internal reflection increases the scattered intensity values, and covering of chamber by isolated material that eliminates the internal reflections. In all samples the result of angular scatter shows a dependence of the scattering angle at a fixed incident angle. Al(2) shows higher values of scattered intensity compared with other samples because it’s a polish surface, that means use of this sample in clinics and laboratories may be hazardous. Also the reflectivity (R) was measured for all samples; reflectivity of aluminum samples is high compare with glass and ceramic. iv ‫‪Peak values of scattering intensity were obtained when the incidence and‬‬ ‫.‪reflectance angle are equal‬‬ ‫‪The reflectivity of all samples varied with the incident angle the high value in‬‬ ‫. )2(‪Al‬‬