近晶A相液晶从均匀的各向同性相中萌生时, 其平直界面失稳后选择具有正弦周期的界面模式作为演化路径。采用偏振光成像的方法测量了几种液晶界面失稳后所选模式的周期。把界面模式作为变量, 以模式的能量泛函积分为作用量, 构建模式选择的唯象模型, 通过数值计算在全域内找到使作用量最小的波数, 这个波数可反映近晶A相液晶界面失稳后实际选择的界面模式的特征。

A flat interface between liquid crystals and isotropic is often unstable when driven away from its equilibrium state. Some transient patterns will be observed at the early stage of the progress. Sinusoidal patterns are observed and measured with polarized microscope in smectic-A liquid crystals growing from uniform isotropic. A phenomenological model of pattern selection is built in the principle of action which produced by integrating over the energy functional. The global minimum wave number can be found by numerical calculation and reflect the characteristics of the actual selected interface pattern.