Effects of granularity on the reflectivity of SmBO₃ powders

Effects of granularity of SmBO₃ powders on the scattering and absorption were analyzed. Mie scattering was mainly considerd for laser protective functional filler against laser scattering. If the mass of laser protective functional filler was constant, the particle size was smaller, particle counts was more, light absorption cross section and the absorption coefficient were greater. For SmBO₃ laser protective functional filler, refractive index n=1.95, the laser wavelength was 1.06μm. It can be obtained that scattering area ratio of was the largest when χ was 1.771 from the diagram of scattering area ratio Q (λ) as a function of particle size parameter χ. At this time, 2πr/λ was 1.771 and so r was about 298nm. Therefore, when the particle size was about 600nm, the scattering extinction of SmBO₃ was the strongest. In the wavelength range of 1.05 to 1.15μm, with the particles growing up, the reflectivity at 1.06μm decreased, and it reached the minimum value of about 0.5% as the particle size was about 587nm. As the particle size further grew up, reflectivity values increased. When the particle size was about 1μm, the reflectivity reached about 0.6%. It was consistent with the result of theoretical calculation that the best scattering extinction particle size of SmBO₃ powders was about 600nm. 1.06μm laser direct tests showed that the reflectivity was the lowest when the granularity of SmBO₃ powders was 600 nm. It was also consistent with the result of theoretical calculation.