Simultaneous control of volumetric light distribution through turbid media using real-time three-dimensional optoacoustic feedback

Focusing light through turbid media presents a highly fascinating challenge in modern biophotonics. The unique capability of optoacoustics for high resolution imaging of light absorption contrast in deep tissues can provide a natural and efficient feedback to control light delivery in scattering medium. While basic feasibility of using optoacoustic readings as a feedback mechanism for wavefront shaping has been recently reported, the suggested approaches may require long acquisition times making them challenging to be translated into realistic tissue environments. In an attempt to significantly accelerate dynamic wavefront shaping capabilities, we present here a feedback-based approach using real-time three-dimensional optoacoustic imaging assisted with genetic-algorithm-based optimization. The new technique offers robust performance in the presence of noisy measurements and can simultaneously control the scattered wave field in an entire volumetric region.Comment: 4 pages, 3 figure

Numerical modeling and measurement by pulsed television holography of ultrasonic displacement maps in plates with through-thickness defects

We present a novel numerical modeling of ultrasonic Lamb and Rayleigh wave propagation and scattering by through-thickness defects like holes and slots in homogeneous plates, and its experimental verification in both near and far field by a self-developed pulsed TV holography system. In contrast to rigorous vectorial formulation of elasticity theory, our model is based on the 2-D scalar wave equation over the plate surface, with specific boundary conditions in the defects and plate edges. The experimental data include complex amplitude maps of the out-of-plane displacements of the plate surface, obtained by a two-step spatiotemporal Fourier transform method. We find a fair match between the numerical and experimental results, which allows for quantitative characterization of the defects

Media 2: Portable spherical array probe for volumetric real-time optoacoustic imaging at centimeter-scale depths

Originally published in Optics Express on 18 November 2013 (oe-21-23-28062

Media 1: Portable spherical array probe for volumetric real-time optoacoustic imaging at centimeter-scale depths

Originally published in Optics Express on 18 November 2013 (oe-21-23-28062

Contradictions in power, sexuality, and consent: An institutional ethnography of male neonatal circumcision

In this dissertation I examine the routinization of prophylactic neonatal male circumcision in hospital settings in New England. Using the methodological framework of Dorothy E. Smith\u27s (1987) Institutional Ethnography, I study the ways in which institutionalized policies and processes regarding this procedure intersect in the lives of expecting parents and parents, as well as with those in the medical community. ^ I focus specifically on medical professionals and parents who interact both directly and indirectly in order to challenge or maintain a uniquely American tradition of male neonatal circumcision. In order to understand the attitudes and opinions of these different groups of people, including anti-circumcision activists, I have used a multi-method approach that combines an analysis of questionnaires, interviews, and ethnographic fieldwork in two hospital settings. During my research, I investigate the ways in which authority is maintained and resisted within hospital settings regarding male circumcision, and how the informed consent process is actually negotiated between parents and medical professionals. This dissertation contributes to sociological literature on organizational processes involving discourse, institutional authority, and the informed consent practices as they are experienced and regularly negotiated by healthcare providers and parents.

Acoustic Scattering Mediated Single Detector Optoacoustic Tomography

Optoacoustic image formation is conventionally based upon ultrasound time-of-flight readings from multiple detection positions. Herein, we exploit acoustic scattering to physically encode the position of optical absorbers in the acquired signals, thus reducing the amount of data required to reconstruct an image from a single waveform. This concept is experimentally tested by including a random distribution of scatterers between the sample and an ultrasound detector array. Ultrasound transmission through a randomized scattering medium was calibrated by raster scanning a light-absorbing microparticle across a Cartesian grid. Image reconstruction from a single time-resolved signal was then enabled with a regularized model-based iterative algorithm relying on the calibration signals. The signal compression efficiency is facilitated by the relatively short acquisition time window needed to capture the entire scattered wave field. The demonstrated feasibility to form an image using a single recorded optoacoustic waveform paves a way to the development of faster and affordable optoacoustic imaging systems