Frequency and Directional Response of a Reflection Type Optical Hydrophone: A Simulation Study
Affiliation Type:
Academia
Keywords:
Hydrophone frequency response, hydrophone measurements, signal processing, deconvolution, field simulation
Abstract:
Reflection type fiber optical hydrophones are popular in HIFU measurements as they can withstand high acoustic pressures. Their frequency response is mainly governed by the geometry of the fiber tip. The classic approach is to assume that the fiber tip behaves as a rigid baffled piston. But this approach has several assumptions which are not fully hold. This results in deviation, that will be analyzed and discussed in this contribution. We use a full multiphysics simulation approach to generate more insight into the actual effects of the ultrasonic fields. We performed 2D axisymmetric frequency domain simulations using COMSOL Multiphysics to find the radiation impedance function of the fiber. The impedance function was also computed for two boundary conditions replacing the fiber: hard (normal velocity = 0) and impedance boundary (ρc) conditions. We simulated the pressure fields and calculated the fiber impedance function and compared it against the classic models that consider the fiber tip as a boundary condition.
