Publications & Presentations

Dual-mode endoscopic probe combining OCT and autofluorescence imaging for inner ear hearing loss diagnosis and therapy guidance

Jesung Park, Jeffrey Cheng, Daniel Lee, Jeffrey Holt, Hannah Goldberg, Gopi Maguluri, John Grimble, and Nicusor Iftimia
SPIE Photonics West/BIOS 2020
San Francisco, CA
February 1, 2020

Proof of Concept study has demonstrated that the combined OCT/AF imaging approach can detect morphological and biochemical changes related to inner ear SNHL.

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OCT/AF technology could be used to diagnose potential causes of SNHL and evaluate the success of the hair cell regeneration therapy approaches.

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© 2020 Physical Sciences Inc. All rights reserved. This work was sponsored by The National Cancer Institute/NIDCD under grant number 1 R43 DC015414-03. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We are very grateful for this support.

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Compact Lidar for Continuous Monitoring of Atmospheric Extinction

Compact Lidar for Continuous Monitoring of Atmospheric Extinction
David M. Sonnenfroh*, Robert J. Minelli, Joseph A.K. Goodwin, and W. Terry Rawlins
SPIE Defense and Commercial Sensing, Orlando, FL, 15 - 19 April 2018

Physical Sciences Inc. is developing an advanced, compact lidar capable of continuous mapping of atmospheric extinction to provide environmental situational awareness for high energy laser weapon operations by the Navy.

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The lidar uses a MicroPulse Lidar architecture and combines a solid state Nd:YLF laser operating at 1 micron with photon counting detectors and advanced aerosol retrieval algorithms. We report on the design of the engineering prototype and provide a summary of the system performance demonstrated during the Comprehensive Atmospheric Boundary Layer Extinction / Turbulence Refinement eXperiment conducted at the Shuttle Landing Facility at Kennedy Space Center in June, 2017.

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Copyright © 2018 Society of Photo-Optical Instrumentation Engineers. This paper was presented at SPIE Defense and Commercial Sensing, Orlando, FL, 15 - 19 April 2018 and is made available as an electronic reprint (preprint) with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

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Standoff Detection from Diffusely Scattering Surfaces using Dual Quantum Cascade Laser Comb Spectroscopy

Standoff Detection from Diffusely Scattering Surfaces using Dual Quantum Cascade Laser Comb Spectroscopy
Joel M. Hensley, Justin M. Brown, Mark G. Allen, Markus Geiser, Pitt Allmendinger, Markus Mangold, Andreas Hugi, Pierre Jouy, and Jérôme Faist
SPIE Defense + Commercial Sensing Conference, Orlando, FL, April 15-19, 2018

Designed dispersion compensated quantum cascade OFC sources at 8 and 10mm

At 8mm demonstrated ~1W cw average power (per laser) at room temperature with comb ~80 cm-1 comb width

Demonstrated surface mass loading sensitivity of few mg/cm2 at standoff distances of 0.3 and 1 meter from diffuse surfaces

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Primary improvement needed: increased bandwidth
–150 cm-1 possible with improve dispersion control
–beyond 150 cm-1, will also require faster detectors or better matching between individual comb spacing

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Acknowledgement of Support and Disclaimer
This material is based upon work supported by the Defense Advanced research Projects Agency (DARPA) under Contract Number W31P4Q 15 C 0083. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of DARPA Program Office

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High-efficiency thermophotovoltaic energy conversion enabled by a metamaterial selective emitter

High-efficiency thermophotovoltaic energy conversion enabled by a metamaterial selective emitter
DAVID N. WOOLF, EMIL A. KADLEC, DON BETHKE, ALBERT D. GRINE, JOHN J. NOGAN, JEFFREY G. CEDERBERG, D. BRUCE BURCKEL, TING SHAN LUK, ERIC A. SHANER, and JOEL M. HENSLEY
Optica Vol. 5, Issue 2, pp. 213-218 (2018) •https://doi.org/10.1364/OPTICA.5.000213

Thermophotovoltaics (TPV) is the process by which photons radiated from a thermal emitter are converted into electrical power via a photovoltaic cell.

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Selective thermal emitters that can survive at temperatures at or above ∼1000°C have the potential to greatly improve the efficiency of TPV energy conversion by restricting the emission of photons with energies below the photovoltaic (PV) cell bandgap energy. In this work, we demonstrated TPV energy conversion using a high-temperature selective emitter, dielectric filter, and 0.6 eV In0.68Ga0.32As photovoltaic cell. We fabricated a passivated platinum and alumina frequency-selective surface by conventional stepper lithography. To our knowledge, this is the first demonstration of TPV energy conversion using a metamaterial emitter. The emitter was heated to >1000°C, and converted electrical power was measured. After accounting for geometry, we demonstrated a thermal-to-electrical power conversion efficiency of 24.1  0.9% at 1055°C. We separately modeled our system consisting of a selective emitter, dielectric filter, and PV cell and found agreement with our measured efficiency and power to within 1%. Our results indicate that high-efficiency TPV generators are possible and are candidates for remote
power generation, combined heat and power, and heat-scavenging applications.

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© 2018 Optical Society of America. This paper was published in Optica Vol. 5, Issue 2, pp. 213-218 (2018) •https://doi.org/10.1364/OPTICA.5.000213 and is made available as an electronic reprint with the permission of OSA. The paper can be found at the OSA website: High-efficiency thermophotovoltaic energy conversion enabled by a metamaterial selective emitter . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

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Spatially resolved modeling and measurements of metastable argon atoms in argon-helium microplasmas

Alan R. Hoskinson, José Gregório, Jeffrey Hopwood, Kristin L. Galbally-Kinney, Steven J. Davis, and Wilson T. Rawlins
Journal of Applied Physics 121, 153302 (2017); https://doi.org/10.1063/1.4981922

Microwave-driven plasmas operating near atmospheric pressure have been shown to be a promising technique for producing the high density of argon metastable atoms required for optically pumped rare gas laser systems. Stable microwave-driven plasmas can be generated at high pressures using microstrip-based resonator circuits.

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We present results from computational modeling and laser absorption measurements of argon metastable densities in such plasmas operating in argon-helium gas mixtures at pressures up to 300 Torr. The model and measurements resolve the plasma characteristics both perpendicular to the substrate surface and along the resonator length. The measurements qualitatively and in many aspects quantitatively confirm the accuracy of the model. The plasmas exhibit distinct behaviors depending on whether the operating gas is mostly argon or mostly helium. In high-argon plasmas, the metastable density has a large peak value but is confined very closely to the electrode surfaces as well as being reduced near the discharge gap itself. In contrast, metastable densities in high helium-fraction mixtures extend through most of the plasma. In all systems, increasing the power extends the region of metastable along the resonator length, while the extent away from the substrate surface remains approximately constant.

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Published by AIP Publishing. Journal of Applied Physics 121, 153302 (2017); https://doi.org/10.1063/1.4981922 Used in accordance with the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Investigation of tissue cellularity at the tip of the core biopsy needle with optical coherence tomography

NICUSOR IFTIMIA, JESUNG PARK, GOPI MAGULURI, SAVITRI KRISHNAMURTHY, AMANDA MCWATTERS, AND SHARJEEL H. SABIR3 "Investigation of tissue cellularity at the tip of the core biopsy needle with optical coherence tomography", Vol. 9. No. 2 1 Feb 2018. Biomedical Optics Express 694-704.
We report the development and the pre-clinical testing of a new technology based on optical coherence tomography (OCT) for investigating tissue composition at the tip of the core biopsy needle.
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While ultrasound, computed tomography, and magnetic resonance imaging are routinely used to guide needle placement within a tumor, they still do not provide the resolution needed to investigate tissue cellularity (ratio between viable tumor and benign stroma) at the needle tip prior to taking a biopsy core. High resolution OCT imaging, however, can be used to investigate tissue morphology at the micron scale, and thus to determine if the biopsy core would likely have the expected composition. Therefore, we implemented this capability within a custom-made biopsy gun and evaluated its capability for a correct estimation of tumor tissue cellularity. A pilot study on a rabbit model of soft tissue cancer has shown the capability of this technique to provide correct evaluation of tumor tissue cellularity in over 85% of the cases. These initial results indicate the potential benefit of the OCT-based approach for improving the success of the core biopsy procedures.
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© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement This paper was published in the Journal of Biomedical Optics, Vol. 9. No. 2 1 Feb 2018. Biomedical Optics Express 694-704.
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