All-optical highly sensitive akinetic sensor for ultrasound detection and photoacoustic imaging

Abstract

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 137 dB/ √ Hz 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. functional photoacoustic microscopy of mouse brain in action," Nat. Methods 12, 407-410 (2015). 7. L. Xi, C. Song, and H. Jiang, "Confocal photoacoustic microscopy using a single multifunctional lens," Opt. Lett. 39, 3328-3331 (2014). 8. J. Gateau, A. Chekkoury, and V. Ntziachristos, "Ultra-wideband three-dimensional optoacoustic tomography," Opt.Lett. 38, 4671-4674 (2013). 9. C. Zhang, T. Ling, S.-L. Chen, and L. J. Guo, "Ultrabroad bandwidth and highly sensitive optical ultrasonic detector for photoacoustic imaging," ACS Photonics 1, 1093-1098 (2014). 10. E. Zhang, J. Laufer, and P. Beard, "Backward-mode multiwavelength photoacoustic scanner using a planar Fabry-Pérot polymer film ultrasound sensor for high-resolution three-dimensional imaging of biological tissues," Appl. Opt. photoacoustic microscopy using a digital micromirror device," Opt. Lett. 38, 1683-2686 (2013).

Wideband linear detector arrays for optoacoustic imaging based on polyvinylidene difluoride films

“…5) are comparable to NEP of the wideband photoacoustic detector array based on a 2-D Fabry-Perot interferometer (0.2 kPa). 16 However, the technologies of single-element purely optical detection of an US are generally much more superior allowing NEPs of 2 to 20 Pa. 17,18 As compared with an earlier reported PPA unit 8 based on a 100-μm-thick PVDF film, our PE LDA and FC LDA units are based on a 25-and 28-μm-thick PVDF films. The main advantage of using the thinner PVDF film is an improved AR (420 μm for PPA, 8 40 μm for PE LDA, and 80 μm for FC LDA).…”

Overview of Ultrasound Detection Technologies for Photoacoustic Imaging

“…CW interferometry is sensitive to temperature drifts and vibrations [42]. More details about the limitations of optical ultrasound detection techniques are given in [42,[176][177][178]. Performance comparison between different optical ultrasound detectors is summarized in Table 6.…”

Local Ultrasonic Resonance Spectroscopy: A Demonstration on Plate Inspection

“…The optical microphone does not have any moving parts, as is normally the case for conventional US receivers (piezoelectric material or membrane). It measures the US directly in the air by measuring the change of the refractive index as acoustic waves travel through the Fabry-Pérot etalon [18,[25][26][27]. However, the housing of the microphone itself (or the etalon mirrors) can have a certain natural behavior which could affect the signal.…”