An electro-optical sensor for surface displacement measurements of compliant coatings

Compliant coatings are now being used in many engineering applications, chiefly in relation to sound absorption and noise shielding. Another, though still controversial, application is their use in the reduction of skin friction drag of moving vessels. The design of a compliant coating to realize the latter goal or to achieve optimum sound absorption is complex and requires the determination of the surface motion characteristics resulting from the hydrodynamic forces [D. M. Bushnell, J. N. Hefner, and R. L. Ash, Phys. Fluids 20, 531 (1977)].