An optical probe for measuring water wave slopes

Abstract

A technique is described for the measurement of water surface slopes, using an inexpensive solid state component which acts as a potentiometer, the variable position contact being made by a spot of light. A highly collimated beam of light from a laser is deflected as it passes through the surface and is made to impinge on the component, allowing a DC output to be derived which is proportional to the surface-induced deviation of the beam. The instrument has been used to measure the highly irregular wave disturbances associated with the spreading of surface active oils on water.