When a parallel light beam illuminates a curved air–liquid interface, a group of self-interference fringes appears in the reflection field in the region near the critical point. A model describing the interface height and slope dependences on the fringe phase supports this observation. The fringe phase function is determined by the fringe image. The height, slope, and curvature of the interface curved by a glass slide and thin rod are measured. The resolution, for the curvature measuring, is up to 0.05$\mathrm{\mu }$m⁻¹. A comparison of the experimental results of the interface height by using the exponential theory verifies this approach’s reliability. A small RMS error shows that the results are in good agreement.

当平行光束照射弯曲的气液界面时，临界点附近区域的反射场中会出现一组自干涉条纹。描述界面高度和斜率依赖于条纹相位的模型支持这一观察结果。条纹相位函数由条纹图像决定。测量由载玻片和细棒弯曲的界面的高度、斜率和曲率。曲率测量分辨率高达0.05$\mathrm{\mu }$米^-1。使用指数理论对界面高度的实验结果进行了比较，验证了该方法的可靠性。小的 RMS 误差表明结果非常一致。