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Portland, OR, United States

Ramella-Roman J.C.,Catholic University of America | Nayak A.,Eunice Kennedy Shriver National Institute of Child Health and Human Development | Prahl S.A.,Oregon Medical Laser Center
Journal of Biomedical Optics | Year: 2011

We present the design and calibration of a spectroscopic sensitive polarimeter. The polarimeter can measure the full Stokes vector in the wavelength range 550 to 750 nm with 1-nm resolution and consists of a fiber-based spectrophotometer, a white light emitting diode light source, two liquid crystal retarders, and one polarizer. Calibration of the system is achieved with a scheme that does not require knowledge of the polarizing elements' orientation or retardation. Six intensity spectra are required to calculate the full spectrum Stokes vector. Error in the polarimeter is less than 5%. We report the Stokes vectors for light transmitted through nonscattering polarizing elements as well as a measurement of the depolarizing properties of chicken muscle at several wavelengths. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Morales Cruzado B.,National Institute of Astrophysics, Optics and Electronics | Prahl S.A.,Oregon Medical Laser Center | Delgado Atencio J.A.,National Institute of Astrophysics, Optics and Electronics | Vazquez Y Montiel S.,National Institute of Astrophysics, Optics and Electronics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Determining optical properties of turbid media has been performed by many research groups using a technique based on iteratively solving the radiative transport equation using the adding doubling technique (IAD). We present a new, alternative method, GA-MCML, for determining optical properties based on a Monte Carlo tech- nique for radiative transport (MCML) guided by a genetics algorithm. The Monte Carlo method is more exible than the adding-doubling technique and can be adapted to a wider range of sample geometries. The genetic algorithm is a robust search technique that is well-adapted to avoiding the local minima in this optimization problem. GA-MCML, has been implemented by modifying the MCML source code to account for two common experimental problems: light losses due to the nite sample size and non-linear integrating sphere eects using Mott's equations. GA-MCML was validated by comparing with IAD method for data acquired at 632.8 nm on a set of phantoms using a single integrating sphere system. The GA-MCML results were equivalent to the IAD technique. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.82K | Year: 2007

Joining severed vessels is a recurring problem in trauma and surgery. The basic technology that uses suture has been available for a long time. Many technologies have been introduced to make vessel suturing water-tight. Any solution to this problem must integrate well with standard medical care. This means that the solution must be safe, effective, acceptable to surgeons, and technologically feasible. We propose a novel two-wavelength laser that allows precise and rapid closure of anastomosis of vessels. An exogenous glue, composed of FDA-approved human serum albumin will be used to increase bond strength and burst pressures. A dissolvable stent, also composed of human serum albumin, will be used to facilitate joining larger vessels and aligning the vessel edges. Laser bonding has not gained widespread clinical acceptance because (1) an exogenous chromophore (indocyanine green) was required, (2) no economical laser sources, (3) large laser beam sizes (4) no internal support for the vessel during anastomosis was available. Advances in laser technology at nLight Corp remove issues (2) and (3). The protocol proposed would eliminate issues (1) and (4) - albumin replaces indocyanine green, and internal support is provided by a solid albumin stent, which dissolves once blood is allowed to flow again.


Duncan D.D.,Portland State University | Fischer D.G.,NASA | Dayton A.,Oregon Medical Laser Center | Prahl S.A.,Oregon Medical Laser Center
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2011

We present a method of using an unmodified differential interference contrast microscope to acquire quantitative information on scatter and absorption of thin tissue samples. A simple calibration process is discussed that uses a standard optical wedge. Subsequently, we present a phase-stepping procedure for acquiring phase gradient information exclusive of absorption effects. The procedure results in two-dimensional maps of the local angular (polar and azimuthal) ray deviation. We demonstrate the calibration process, discuss details of the phase-stepping algorithm, and present representative results for a porcine skin sample. © 2011 Optical Society of America. Source


Dayton A.,Oregon Health And Science University | Dayton A.,Oregon Medical Laser Center | Soot L.,The Oregon Clinic Westside Surgical Specialists | Wolf R.,The Oregon Clinic Gastrointestinal and Minimally Invasive Surgery Division | And 3 more authors.
Journal of Biophotonics | Year: 2011

Despite numerous advances, lumpectomy remains a challenging procedure. We report on the early use of light-guided lumpectomy. Eight patients with non-palpable breast cancer undergoing lumpectomy for biopsy-proven and radiographically identifiable cancer were enrolled in the study. An optical wire was designed that incorporated a standard hook-wire with an optical fiber. The optical wire was placed in the same manner as a standard hook-wire. During light-guided lumpectomy, an eye-safe laser illuminated the optical wire and created a sphere of light surrounding the cancer. The light was visible at the beginning of each surgery and facilitated approaching the cancer without using the wire. Dissection around the sphere of light kept the wire tip within the surgical specimen. Three of eight initial surgical specimens had focally positive margins. Additional cavity shaves were performed during five lumpectomies and resulted in negative margins in seven of eight patients. Light-guided lumpectomy is a minor change to breast conserving surgery that can be easily incorporated into clinical practice. Further investigation into the clinical benefit of light-guided lumpectomy is warranted. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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