Frequency-Coded Optical-Actuator Pressure Sensing

A hollow glass tube is configured both as an oscillating cantilever and, by way of distortions of the tube walls, as a transducer of fluid pressure. Excitation of the vibration, whose frequency is a representation of pressure, and readout of the resultant motion, is carried out over long, multimode fibers. The excitation process is thermal via differential expansion effects between tube and a deposited layer. The device constitutes an all-optical, frequency-coded fiber pressure sensor.