溶胶-凝胶法制备用于氟磷酸盐玻璃的氟化镁减反射膜

Magnesium Fluoride Anti-Reflective Films for Fluorophosphate Glass Prepared by Sol-Gel Method

以甲醇镁与氢氟酸为原料,用溶胶-凝胶法,在惰性气氛和常温常压条件下制备了稳定的MgF2溶胶。利用透射电子显微镜观察溶胶颗粒的形貌与尺寸,结果显示溶胶颗粒是由10nm左右的晶粒聚集而成。X射线衍射分析表明,凝胶粉末和薄膜为典型四方晶相结构的MgF2,晶粒尺寸为8.9nm。通过提拉法在精密加工的氟磷酸盐玻璃基底上制备MgF2减反射薄膜。采用原子力显微镜观察薄膜的表面形貌,膜层表面较平整,其均方根粗糙度最低为1.6nm。薄膜的紫外可见光谱测试表明膜层对氟磷酸盐玻璃基底具有较好光学减反效果,在351nm波长处透射率最高可增加6.49%,大大提高了氟磷酸盐玻璃的透射率。使用351nm脉冲(脉宽8ns)激光测试薄膜的激光损伤阈值,薄膜和基底的损伤阈值都高于35J.cm-2。

Stable MgF2 sols are synthesized by sol-gel method under nitrogen atmosphere at room temperature, with magnesium methoxide and hydrofluoric acid aqueous solution as reactants. Characterized by transmission electron microscopy, MgF2 sols are accumulated by irregular particles of about 10 nm diameter. The X-ray diffraction results that xerogels and films all show tetragonal crystalline MgF2 and the average grain size is about 8. 9 nm. With prepared MgF2 sols, MgF2 anti-reflective films are dip-coated on well-polished and well-cleared fluorophosphate glass substrates. Atomic force microscope images of films indicate that the surfaces of films are very smooth, and the root mean square roughness is as small as 1.6 nm. At 351 nm wavelength, the transmittance of fluorophosphate glass coated by anti-reflective film is 6.49 % higher than that of the substrate. The laser damage thresholds of films and substrate are both higher than 35 J.cm 2, tested by 351 nm pulse laser （8 ns pulse width）.