Airflow detection system using fiber optics

Claim 1

A sensor, for providing an optical signal indicative of the presence of fluid flow in a plenum, in a system having an optical signal detector and optical signal source, comprising: displacement means, having a chamber for receiving fluid flow from the plenum and including a cantilevered member disposed therein, said cantilevered member oscillating at a sensor characteristic frequency in response to fluid flow through said chamber; and first and second optical sections having an optical surface on each end thereof, said sections arranged end to end on a major surface of said cantilevered member such that a first end of each form, in combination, an optical coupling, said coupling adapted to flex with oscillation of said cantilevered member, the opposite end of said first and second sections being optically aligned with the optical signal source and the optical signal detector, respectively, to couple optical signals from the signal source through said optical coupling to the dectector, whereby oscillation of said member in the presence of fluid flow produces an oscillatory misalignment of said optical coupling to further provide intensity modulation of such optical signals at the sensor characteristic frequency.