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source: © 2018 Optical Society of America

We develop a simple model for assessing the sensitivity of silicon-photonics ultrasound interferometric detectors for two types of acoustic waves. The sensitivity of the two polarization modes of a waveguide are calculated and experimentally verified. [Read More…]

Fig. 2. (a) Microscope image of the SOI sensor. PMF is polarizationmaintaining fiber (b) Schematic illustration of the interferometric setup. PZ is piezoelectric fiber stretcher; VA is variable attenuator;DL is delay line. For each polarization state, two types of acoustic waves were detected: (c) longitudinal waves in normal incidence and (d) surface acoustic waves created in oblique incidence.

Fig. 3. Measured time-dependent acoustic responses (optical phase shift) for TE (solid) and TM (dashed) waveguide modes, obtained for (a) glass fiber, (b) silicon waveguide with normal incidence and (c) silicon waveguide with surface acoustic waves created in oblique incidence.

S. Tsesses, D. Aronovich, A. Grinberg, E. Hahamovich, and A. Rosenthal, “Modeling of ultrasound detection by silicon-photonics-based sensors,” in Advanced Photonics 2018 (BGPP, IPR, NP, NOMA, Sensors, Networks, SPPCom, SOF), OSA Technical Digest (online) (Optical Society of America, 2018), paper JTu2A.43.

source: © 2018 Optical Society of America

Optical detection of ultrasound is often characterized by limited dynamic range and lack of scalability. In this work, we present passive pulse interferometry (P-PI) as a solution to both these challenges.[Read More…]

Fig. 1. (a) A schematic drawing of the system used for pulse interferometry. (b) Active demodulation scheme consists of an unbalanced Mach-Zenhder interferometer (MZI) stabilized to quadrature using a wideband feedback circuit. PZ is piezoelectric fiber stretcher and FC is 50/50 fused fiber coupler. (c) Passive demodulation scheme consists of a dual-polarization unbalanced MZI, implementing a 90° optical hybrid. PBS is polarization beam splitter. (d) A schematic drawing of the system used for CW interrogation

Y. Hazan and A. Rosenthal, “Passive pulse interferometry for optical detection of ultrasound with a large dynamic range,” in Advanced Photonics 2018 (BGPP, IPR, NP, NOMA, Sensors, Networks, SPPCom, SOF), OSA Technical Digest (online) (Optical Society of America, 2018), paper SeTh2E.5.

source: © 2018 Optical Society of America

We analyze the response of negatively focused acoustic detectors in both time and frequency domains and show how the approximations made in the virtual detector approach lead to image distortion and artifacts.
[Read More…]

Fig. 2. Simulated reconstruction results with a negatively focused detector for circular symmetry of (a) Gaussian absorbers of various sizes obtained
using (b) model-based reconstruction with the virtual-detector approach (c) and the exact model matrix that includes the response of the detector.
(d) Comparison of the reconstructed amplitude of the Gaussian sources by the virtual detector approach (Fig. 3b) as a function of their diameter,
and the prediction of the d model shown in Fig. 2.

G. Drozdov and A. Rosenthal, “Analysis of reconstruction errors in optoacoustic tomography with negatively focused ultrasound detectors,” in Biophotonics Congress: Biomedical Optics Congress 2018 (Microscopy/Translational/Brain/OTS), OSA Technical Digest (Optical Society of America, 2018), paper OW4D.6.

source: © 2018 Optical Society of America

A novel method for determining back-projection operators is developed and demonstrated in optoacoustic tomography. The proposed method may be generalized for any imaging surface or detector shape. [Read More…]

Fig. 1. An illustration of how the back-projection operator is applied on data from different detectors. The back-projected images are shown by the arcs and the region of interest is shown in gray. The final reconstruction is a sum of all the back-projected images.

Amir Rosenthal, “Algebraic calculation of back-projection operators in optoacoustic tomography,” Optical Society of America (2018)

source:© 2017 Optical Society of America

To enable quantitative molecular and morphological readings in vivo, a near-infrared fluorescence (NIRF)-IVUS catheter and a novel correction algorithm were engineered. Hybrid imaging was validated in atherosclerotic rabbit model in vivo.[Read More…]

Fig 2. In vivo cNIRF-IVUS imaging of inflammation in atherosclerosis.cNIRF-IVUS in vivo imaging of atherosclerosis-related inflammation inside a rabbit aorta revealed two areas (12-30mm and 38-50mm at Fig. 2a, c) of elevated NIR fluorescence activity with a 7mm lower NIRF signal in between. The same fluorescence distribution was observed on the ex vivo FRI image (Fig. 2b). Representative cross-sectional cNIRF-IVUS images at pullback position 1 and 2 (at Fig. 2a) are shown in Fig. 2d and e.

D. Bozhko, E. A. Osborn, A. Rosenthal, J. W. H. Verjans, T. Hara, J. R. McCarthy, S. Kellnberger, G. Wissmeyer, A. Mauskapf, A. F. Stein, F. A. Jaffer, and V. Ntziachristos, “Quantitative Intravascular Fluorescence-Ultrasound Imaging In Vivo,” in Optics in the Life Sciences Congress, OSA Technical Digest (online) (Optical Society of America, 2017), paper OmM2D.3.