A novel all-optical akinetic ultrasound sensor, consisting of a rigid, fiber-coupled Fabry-Pérot etalon with a transparent central opening is presented. The sensing principle relies exclusively on the detection of pressure-induced changes of the refractive index in the fluid filling the Fabry-Pérot cavity. This enables resonance-free, inherently linear signal detection over a broad bandwidth. We demonstrate that the sensor achieves a exceptionally low peak noise equivalent pressure (NEP) values of 2 Pa over a 20 MHz measurement bandwidth (without signal averaging), while maintaining a flat frequency response, and a detection bandwidth up to 22.5 MHz (−6 dB). The measured large full field of view of the sensor is 2.7 mm × 1.3 mm and the dynamic range is or 63 dB at 20 MHz bandwidth. For different required amplitude ranges the upper amplitude detection limit can be customized from at least 2 kPa to 2 MPa by using cavity mirrors with a lower optical reflectivity. Imaging tests on a resolution target and on biological tissue show the excellent suitability of the akinetic sensor for optical resolution photoacoustic microscopy (OR-PAM) applications.
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机译:提出了一种新颖的全光学动能超声传感器,该传感器由刚性,光纤耦合的Fabry-Pérot标准具和一个透明的中央开口组成。传感原理完全依赖于检测压力引起的填充Fabry-Pérot腔的流体中折射率的变化。这样可以在较宽的带宽上实现无共振,固有的线性信号检测。我们证明了该传感器在20 MHz的测量带宽(不进行信号平均)的情况下可实现2 Pa的极低峰值噪声等效压力(NEP)值,同时保持平坦的频率响应以及高达22.5 MHz(-6的检测带宽) D b)。测得的传感器大全视野为2.7 mm×1.3 mm,动态范围为展开▼