基于非余弦膜厚计算公式,提出了利用极坐标简化表征膜厚分布的方法,对单源电子束蒸发的光学薄膜的膜厚均匀性控制进行了研究,同时对修正板的放置位置进行了计算。相对于传统修正板置于蒸发源正上方的方法,采用极坐标法计算得到的修正板位置更有利于控制膜厚分布的均匀性。以蒸发H4和MgF2为例,分别对高、低折射率材料的修正板位置和形状进行计算,并利用这两种材料分别制备单层膜,实测光谱均匀性偏差优于0.3%,证明了所提方法的正确性与可行性。

A simplified polar coordinate method based on the non-cosine film thickness formula is proposed for characterizing film thickness distribution. Herein, control of the uniformity of optical film thickness formed by single source electron beam evaporation is studied. Simultaneously, the position of the mask plate is calculated. Compared to the traditional method of placing the mask directly above the evaporation source, the proposed polar coordinate method is used to calculate mask position, which is more conducive to controlling the uniformity of film thickness distribution. Considering an evaporated H4/MgF₂ combination as an example, the mask positions and shapes of high and low refractive index materials are calculated, and single layer films are prepared using these two materials. The measured spectral uniformity deviation is better than 0.3%, thus demonstrating the correctness and feasibility of the proposed method.