Engineering a portable quasi-distributed Fibre-Bragg-Grating temperature sensing system for clinical hyperthermia

We have developed a quasi-distributed temperature sensor consisting of an array of fibre Bragg gratings (FBGs), illuminated by a superluminescent diode (SLD) and interrogated by a fibre Fabry-Perot (FFP) tunable filter. This sensor has been previously tested both on agar-gel tissue phantoms and in vivo on tumours, in rabbit livers that were treated by hyperthermia. The FFP filter is controlled by a piezoelectric transducer operating in an open-loop configuration, and this introduces repeatability and long-term stability issues. Here we report the further development of this system in order to account for the FFP filter issues, and we reduce the noise levels to less than 0.035/spl deg/C rms and the long-term temperature drift below 0.1 /spl deg/C/hr.