Fibre optic sensor – Broadband (for FOHS V2)
The Fibre-optic Hydrophone System (FOHS) offers the smallest active element of any hydrophone in the Precision Acoustics Ltd product range. It is immune to Electro-Magnetic Interference and is thus ideal for a wide range of applications at frequencies from 1.0 MHz to 40 MHz, especially therapeutic ultrasound. It can also measure temperature change and thus enables users to simultaneously measure pressure waveforms and the ultrasonically induced heating arising from their absorption within the surrounding medium. The fibre sensor and mounting chuck are also non-ferrous and therefore compatible for use with MRI equipment.
Precision Acoustics Ltd offers two variants of fibre-optic hydrophone: standard and broadband. The only noteworthy difference between the two offerings is the less substantial drop in sensitivity of the broadband fibre variant between 18-22 MHz. The difference in frequency response between these two fibre types is depicted in the figure. This feature is a known characteristic of the sensor and is related to the geometry of the sensor.