OPTICAL-FIBER PHOTOACOUSTIC-PHOTOTHERMAL PROBE

We describe the operation of an all-optical probe that provides an alt ernative means of implementing photoacoustic and photothermal investig ative techniques, particularly those used in biomedical applications. The probe is based on a transparent, acoustically and thermally sensit ive Fabry-Perot polymer film sensor mounted at the end of an optical f iber. We demonstrate the ability of the system to make photoacoustic a nd photothermal measurements simultaneously and evaluate its photother mal response, using a nonscattering liquid target of known and adjusta ble absorption coefficient. The acoustic and thermal noise floors were 2 kPa and 6 x 10(-8) degrees C, respectively, obtained over a 25-MHz measurement bandwidth and 30 signal averages. (C) 1998 Optical Society of America.