All optical highly sensitive broadband ultrasound sensor without any deformable parts for photoacoustic imaging
We present a novel akinetic optical ultrasound sensor, consisting of a rigid, fiber coupled Fabry P'erot interferometer (FPI) with a central opening. The sensing principle relies exclusively on the detection of pressure induced changes of the refractive index in the liquid located between the cavity mirrors. This enables resonance free, inherently linear signal detection over a large bandwidth. We demonstrate that the sensor allows to realize exceedingly low noise equivalent pressure (NEP) values of 2 Pa over a 20 MHz measurement bandwidth, while maintaining a large full field of view of 2,7mm x 1,3mm as well as a flat frequency response. Imaging tests on phantoms and biological tissue show the suitability of the XARION sensor for optical resolution photoacoustic microscopy (OR PAM) applications. Transparent in axial direction, the sensor facilitates the implementation of highly sensitive fast scanning reflection mode OR PAM setups, as well as easy integration with other imaging modalities such as confocal microscopy or OCT.
SPIE BiOS