Fiber-optic microphones for battlefield acoustics

Abstract

We describe recent work to evaluate the potential performance of an interferometric fiber-optic microphone for battlefield acoustics. The microphone design has high sensitivity and flat response at low frequency and is readily multiplexed. The design is simple and could be manufactured at low cost, which is desirable since in operation the sensors may need to be disposable. Field trial results from an array of microphones are discussed.

An Infrasound Sensor Based on Extrinsic Fiber-Optic Fabry–Perot Interferometer Structure

“…OW-frequency infrasound detection is of great significance because of its wide applications in the fields of the early warning of natural disasters such as earthquakes [1], volcanic eruptions [2], explosions [3], hydrophone [4], even battlefield [5]. The traditional methods for low-frequency infrasound detection can be divided into two broad categories: capacitive and piezoelectric.…”

A novel highly sensitive optical fiber microphone based on single mode–multimode–single mode structure

“…This means that the FOM can work in some difficult measurement environments such as inside magnetic resonance medical imaging equipment and in other industrial applications subject to high electromagnetic fields. A number of different optical fiber microphone schemes have been reported, employing a fiber Bragg grating [1, 2], reflective membrane [3], fiber DFB laser [4], and an interferometer [5, 6]. However by comparison to a conventional microphone, the cost of available FOMs is not competitive since the sensing schemes often require expensive sensor components and complex demodulation systems to achieve a high sensitivity to the weak acoustic pressure.…”

Reflectometry based on a frequency-shifted interferometer using sideband interference

“…An array of discrete (or so-called quasi-distributed) fiber-optic sensors can be interrogated by a single measurement system, which allows one to conveniently monitor the parameters of interest over a long range. This ability brings about new applications in many areas, such as structural health monitoring [1], oil down hole monitoring [2], and homeland security [3].Commonly used fiber-optic sensor multiplexing techniques include wavelength-division multiplexing (WDM) [4], time-division multiplexing (TDM) [5], frequencydivision multiplexing (FDM) [6,7], or their combinations or variations. In a WDM system, as each sensor must operate within a distinct wavelength range, the sensor number is limited by the ratio of available source bandwidth to the allocated sensor wavelength range.…”

“…An array of discrete (or so-called quasi-distributed) fiber-optic sensors can be interrogated by a single measurement system, which allows one to conveniently monitor the parameters of interest over a long range. This ability brings about new applications in many areas, such as structural health monitoring [1], oil down hole monitoring [2], and homeland security [3].…”