A novel orthogonal transmission-virtual grating method and its applications in measuring micro 3-D shape of deformed liquid surface

Deformed liquid surface directly involves the surface tension, which can always be used to account for the kinematics of aquatic insects in gas–liquid interface and the light metal floating on the water surface. In this paper a novel method based upon deformed transmission-virtual grating is proposed for determination of deformed liquid surface. By addressing an orthogonal grating (1–5 line/mm) under the transparent water groove and then capturing images from upset of the deformed water surface, a displacement vector of full-field which directly associates the 3-D deformed liquid surface then can be evaluated by processing the recorded deformed fringe pattern in the two directions (x- and y-direction). Theories and equations for the method are thoroughly delivered. Validation test to measure the deformed water surface caused by a Chinese 1-cent coin has been conducted to demonstrate the ability of the developed method. The obtained results show that the method is robust in determination of micro 3-D surface of deformed liquid with a submicron scale resolution and with a wide range application scope.

► We propose a novel method for measuring deformed liquid surface.
► Mathematic relations of the method are theoretically derived.
► Validation test is conducted to demonstrate the ability of the method.
► Performance of the method is estimated.