Critical light reflection from curved liquid surface

A critical light reflection from curved liquid surfaces was discovered. It is shown that if a collimated light beam illumines the curved liquid surface, the special reflective patterns, which correspond to the critical reflection, can be produced. In fact, high visibility diffraction fringes, which resulted from the critical boundary limitation of the reflection wave front, were experimentally observed near the boundary. The surface height was obtained directly from measuring the dark central region width of the reflection pattern and then the surface profile was calculated numerically. It is believed that the critical reflection field is capable of real time characterization of curved liquid surface.