弯月面法涂覆SiO_(2)溶胶凝胶增透膜厚度与均匀性研究

Study on Thickness and Uniformity of Anti-reflective Film of Silica Sol-gel Coated by Meniscus Method

为在光学元件表面涂覆特定膜厚且均匀性好的SiO_(2)溶胶凝胶增透膜,使用自研的弯月面涂胶机在200 mm×200 mm的熔石英平板上进行SiO_(2)溶胶凝胶增透膜的涂覆。基于薄膜干涉的原理,搭建了一套膜厚测试系统,准确获得了基片上的膜厚分布;对薄膜厚度与涂覆速度的关系进行幂函数拟合,并分析了弯月面涂胶机的涂覆速率及倾斜角度对薄膜厚度与均匀性的影响。结果表明,当涂胶机水平放置时,薄膜厚度与涂覆速率的拟合关系符合弯月面涂覆理论公式,薄膜厚度随涂覆速率的增加而增大,而膜厚均匀性随涂覆速率的增加先增大后减小。当涂覆速率为1.69 mm/s左右时,膜厚均匀性达到最佳,相对标准偏差为0.017。当涂覆速率为1.69 mm/s固定不变,涂胶机的倾斜角度在0°~10°范围内变化时,倾角越大,薄膜厚度越小,倾角在10°比在0°时厚度减小了约38%,而膜厚均匀性随倾斜角度变化不大,小于5%,可以忽略。

In order to coat the anti-reflective film of silica sol-gel with a specific film thickness and good uniformity on the surface of the optical element,the anti-reflective film of silica sol-gel was coated on a 200 mm×200 mm fused silica plate using a self-developed meniscus coating machine.Based on the principle of film interference,a set of film thickness measurement system was built to accurately obtain the film thickness distribution on the substrate;The relationship between the film thickness and the coating rate was fitted with a power function,and the influence of the coating rate and the inclination angle of the meniscus coating machine on the film thickness and uniformity was analyzed.The results show that when the coating machine is placed horizontally,the fitting relationship between the film thickness and the coating rate conforms to the meniscus coating theory formula.The film thickness increases with the coating rate,the film thickness uniformity first increases and then decreases with the coating rate.When the coating rate is about 1.69 mm/s,the film thickness uniformity reaches the best,and the relative standard deviation is 0.017.When the coating rate is fixed at 1.69 mm/s and the inclination angle of the gluing machine changes within the range of 0°~10°,the larger the inclination angle,the smaller the film thickness.When the inclination angle is 10°,the thickness is reduced by about 38%relative to that at 0°,and the film thickness uniformity does not change much with the inclination angle,which is less than 5%and can be ignored.