Description

Fibre-optic Hydrophones

For more information see the paper “A Fabry–Pérot fiber-optic ultrasonic hydrophone for the simultaneous measurement of temperature and acoustic pressure” in J. Acoust. Soc. Am, Vol. 125, No. 6, page 3611, June 2009.

The fibre optic hydrophone is the latest addition to our hydrophone range. Despite its 10um active diameter the sensitivity is similar to larger element needle hydrophones. This, coupled with, its immunity from electro-magnetic radiation makes it particularly suited for high frequency measurements in hostile fields.

The system can be used in high intensity fields where needle or membrane hydrophones may experience serious damage. Replacement fibres are readily available and inexpensive.

The hydrophone can be used to measure temperature and pressure, at the same time, and at the same point in the field. This enables a direct correlation to be made between pressure and thermal change.

Two version of the fibre-optic hydrophone sensors are available, a plane tipped sensor for optimal sensitivity (but which has less uniform frequency response) and a tapered tipped sensor for optimal frequency response (but which has a slightly lower sensitivity).

Fibre Optic Hydrophone

System supplied with replacement fibres.

Tapered Tip

Tapered fibre tip to ensure optimum frequency response over a wide frequency range.

Technical Specifications

Output Impedance:	50 ohm terminated system
Typical Probe Sensitivity:	plain sensor 150mV/MPa at 3MHz tapered sensor 100mV/MPa at 3MHz
Sensitivity Tolerance:	Sensitivity variation between individual probes is approx. +/-3dB
Usable Frequency range:	250kHz to 50MHz (may require calibration at NPL, London for some frequency ranges)
Dynamic range:	10kPa to 15MPa. Note the system has been tested in a field in excess of 700Wcm-2 with no damage
Typical Frequency Response:	to be advised please contact us
Sensor Material:	10 micron parylene on glass backing
Sensor Dimension:	10 micron diameter