Photoacoustic signal measurement using thin film Fabry-Perot optical interferometer for photoacoustic microscopy

A photoacoustic signal measurement system using Fabry-Perot optical interferometer (FPI) for microscopy is presented. Most of the photoacoustic imaging systems have limitation by opaque ultrasound transducer in the alignment system setup. Thus, the excitation laser source should avoid the transducer to illuminate a sample, which makes the system difficult to build-up. To solve this difficulty, a FPI based on Polydimethylsiloxane (PDMS) thin film has been implemented and applied to measure the acoustic wave signal in this work. A tunable laser was used for choosing the Q-point at which the signal has the highest and/or linear response to the signal generated from the sample. When the acoustic wave arrives the PDMS film surface, its thickness is modulated, which affect the FPI interference signal and allows to have noncontact measurement of the photoacoustic signal.