Diffractive optic fluid shear stress sensor

Recent advances in the design and fabrication of integrated diffractive optical elements has resulted in the development of a small and integrated micro-optical shear stress sensor. Miniaturization of these sensors has been achieved by integrating the collective function of a large number of refractive optical elements onto a single substrate without the loss of functionality and efficiency. This paper describes the fabrication of the micro-shear stress sensor and an experiment designed for the evaluation of its performance. The results show that, the micro-optical shear stress sensor accurately measures the wall velocity gradient for all laminar flows and for turbulent flows with moderate Reynolds numbers