Parallel self-mixing flow sensor using monolithic VCSEL array

This paper describes the first multi-channel velocity sensor based on a self mixing effect in a monolithic VCSEL array. The self-mixing signals are obtained directly via the feedback caused variation in laser junction voltage, omitting the need for a photodetector. This solution, enabling concurrent acquisition of a plurality of signals, offers significant technological advantage over single channel implementation as it removes the need to scan the target in a raster fashion. In comparison with the spot-raster imaging sensors, the acquisition time is significantly shortened - the mechanical scanning process in is replaced by concurrent acquisition of several channels enabling flow velocity to be sensed on a 2D grid by performing a single sweep of the area. The system was used to measure the velocity profile of fluid flow resembling that of blood circulation in peripheral blood vessels.