All-optical airflow sensor enables simultaneous speed and direction measurement.

ABSTRACT

Aiming to achieve simultaneous measurement of airflow speed and direction with high accuracy, a new all-optical airflow sensor based on triangulation concept is proposed. It consists of a suspending tapered fiber tip and a multicore fiber, acting as the flow interaction element and the localization reference, respectively. During operation, the detection light emitted from the tapered fiber will be coupled to the multicore fiber. Upon exposure to airflow, the induced deflection of the tapered fiber tip will change the individual receiving optical powers of the three cores arranged into triangular pattern, which are dependent on both of the flow speed and direction. Through properly designing structure parameters as core spacing, suspending length, tip diameter and axial fiber distance, the omnidirectional airflow with flow speed within 90 mm/s has been experimentally measured with high fidelity.