PROFILOMETRY OF A LIQUID-FREE SURFACE WITH LARGE SLOPE VARIATIONS

We describe and test a refractive method for determining the height pr ofile of an unsteady Liquid-free surface, which is adequate for region s where the slope of the surface changes strongly, as for example the head of a spreading current. The method is developed for situations in which the height depends on a single Cartesian coordinate (plane flow s); however, the underlying idea could be applied to more general case s. As a test, we obtained the profiles of a transparent solid object ( a cylindrical lens) and of an actual Liquid how. These profiles are de termined with high accuracy even if the direction of the normal to the free surface changes approximately 150 degrees within the probed regi on. (C) 1997 Optical Society of America.