Micro-Optical Sensors for Boundary Layer Flow Studies

This manuscript describes optical MEMS (or MOEMS)-based microsensors for near wall boundary layer flow and particle field analysis. The sensors have been developed to measure a variety of parameters including flow velocity, surface speed, skin friction, and particle sizing. The surface mounted sensors measure flow velocity and/or flow velocity gradients as close as 70 microns from the wall. The sensors have been successfully used in a number of filed tests and flow facilities at different Reynolds numbers. They have also been used on-board full-scale vehicles. These compact and embeddable sensors incorporate specially designed diffractive optical elements and use single-mode optical fiber or integrated diode lasers for illumination.