在极地环境(如南极Dome A)中的光学系统，氧化铟锡(ITO)薄膜加热除霜有突出的优势。简述了ITO 薄膜除霜原理，指出了目前采用的直流电、点状电极的加热设计存在局部过冷、电极过热、整体加热不均的情况，影响成像质量与除霜效果。给出了加热除霜效果的评估指标，提出了多相交流电、线状电极的新设计，并采用“主路径”分析法进行论证。然后以南极巡天望远镜(AST)为背景，对500 mm 口径镜面进行有限元模拟，在等功率条件下，对各加热设计进行评估。使用红外热像仪测量实际镜面：采用新设计后，镜面温度均方差降低了81.65%，峰谷值降低了76.31%。实验结果表明：新设计大幅提高了加热除霜的均匀性和效率，改善了视宁度，有望应用于南极光学望远镜工程中。

For optical system working in the polar environment, such as Antarctic Dome A, ITO film defrosting has outstanding advantage. The principle of ITO film defrosting is introduced. Present heating design for DC load with spot electrodes has several limitations: large area of local insufficient heating, electrode area overheating and uneven distribution on the whole surface. These affect imaging quality and defrosting effect. The evaluation index for defrosting effect is given, and then the new design of multiple-phase AC load with linear electrodes is put forward. It is analyzed using main path method. Targeting Antarctic Survey Telescope (AST), a 500 mm aperture mirror is studied using finite element method: each heating design is evaluated under equal power condition. The actual mirror is measured by infrared thermal imager. Using the new design, mean square deviation of mirror temperature reduces by 81.65% and peak to valley by 76.31%. The experimental results validate that the design of multiple phase AC load with linear electrodes greatly improves defrosting homogeneity, effectiveness and seeing. It will be applied to Antarctic optical telescope engineering.