Influence of deposition temperature on properties of LaF3 coating

LaF3 single-layer coatings were prepared by thermal boat evaporation at the deposition temperatures of 189, 255, 277 and 321 ℃ respectively. The crystal structures of the coatings were characterized by X-ray diffraction(XRD). A spectrophotometer was employed to measure its transmittance. Moreover, refractive index, extinction coefficient and cut-off wavelength were obtained from the measured transmittance spectral curve. The residual stress was evaluated by the Stoney’s equation and optical interferometer. Laser induce damage threshold(LIDT) was performed by a tripled Nd: YAG laser system. The results show that the crystallization status becomes better with the deposition temperature increasing. Correspondingly, the grain size also gets larger. Meanwhile, the coatings become more compact