A multiwavelength, high bandwidth (1 GHz) frequency–domain photon migration (FDPM) instrument has been developed for quantitative, non–invasive measurements of tissue optical and physiological properties. The produces 300 kHz to 1 GHz density waves (PDWs) in optically turbid media using a network analyser, an avalanche photodiode detector four amplitude–modulated diode lasers (674 nm, 811 849 nm 956 nm). frequency–dependence PDW phase amplitude is measured compared analytically derived model...

We investigate experimentally the physical processes underlying pulsed cellular microsurgery and micromanipulation using nanosecond 532- 1064-nm laser pulses focused at high numerical aperture. find that parameters employed for many microirradiation techniques are congruent with those leading to optical breakdown in water. determine size shape of laser-induced plasma, pressure emitted shock wave, energy cavitation bubble formed by expanding plasma. discuss implications results biophysical procedures.

We demonstrate a novel strategy for mixing solutions and initiating chemical reactions in microfluidic systems. This method utilizes highly focused nanosecond laser pulses from Q-switched Nd:YAG at lambda = 532 nm to generate cavitation bubbles within 100- 200-microm-wide channels containing the parallel laminar flow of two fluids. The bubble expansion subsequent collapse channel disrupts fluid streams produces localized region mixed fluid. use time-resolved imaging fluorescence detection...

We introduce a novel and efficient method to provide solutions inverse photon migration problems in heterogeneous turbid media. The extracts derivative information from single Monte Carlo simulation permit the rapid determination of rates change detected signal with respect perturbations background tissue optical properties. then feed this nonlinear optimization algorithm determine properties heterogeneity under examination. demonstrate use approach solve rapidly two-region problem transport...

We use time-resolved imaging to examine the lysis dynamics of non-adherent BAF-3 cells within a microfluidic channel produced by delivery single highly-focused 540 ps duration laser pulses at λ = 532 nm. Time-resolved bright-field images reveal that pulsed microbeam results in formation laser-induced plasma followed shock wave emission and cavitation bubble formation. The confinement offered constrains substantially expansion significant deformation PDMS walls. To cell dispersal cellular...

Using time-resolved imaging, we investigated the lysis of confluent PtK2 cell cultures by pulsed laser microbeam irradiation. Images obtained at time delays 0.5 ns to 50 μs demonstrate be mediated laser-induced plasma formation resulting in pressure wave propagation and cavitation bubble formation. Image analysis enabled quantitative characterization dynamics. The zone damage exceeded size serves implicate expansion as primary agent injury.

The diffusion approximation to the Boltzmann transport equation is commonly used analyze data obtained from biomedical optical diagnostic techniques. Unfortunately, this has significant limitations accurately predict radiative in turbid media, which constrains its applicability highly scattering systems. Here we extend both stationary and frequency-domain cases using an approach initially formulated independently by Prahl [Ph.D. thesis, University of Texas at Austin, 1988 (unpublished)] Star...

The generation of arbitrarily shaped nonspherical laser-induced cavitation bubbles is demonstrated with a optical technique. are formed using laser intensity patterns by spatial light modulator linear absorption inside liquid gap thickness $40\text{ }\ensuremath{\mu}\text{m}$. In particular we demonstrate the dynamics elliptic, toroidal, square, and V-shaped bubbles. bubble recorded high-speed camera at framing rates up to $300\text{ }000$ frames per second. observed evolution compared...

Background and Objective The purpose of this study was to compare the ablation cortical bone at wavelengths across near midinfrared region. Study Design/Materials Methods An free electron laser generating 4-μs macropulses specific between 2.9 9.2 μm used ablate bone. same pulse intensity, repetition rate, radiant exposure, number pulses, delivery for each wavelength. Tissue removal, collateral thermal injury, morphologic characteristics sites were measured by light scanning microscopy,...

Using the -P1 approximation to Boltzmann transport equation we develop analytic solutions for fluence rate produced by planar (1-D) and Gaussian beam (2-D) irradiation of a homogeneous, turbid, semi-infinite medium. To assess performance these compare predictions two metrics optical penetration depth with Monte Carlo simulations. We provide results under both refractive-index matched mismatched conditions properties where ratio reduced scattering absorption lies in range 0(µ/µa)104. For...

Abstract Cell lysis and molecular delivery in confluent monolayers of PtK 2 cells are achieved by the 6 ns, λ = 532 nm laser pulses via a 40×, 0.8 NA microscope objective. With increasing distance from point focus we find regions (a) immediate cell lysis; (b) necrotic that detach during fluorescence assays; (c) permeabilized sufficient to facilitate uptake small (3 kDa) FITC‐conjugated Dextran molecules viable cells; (d) unaffected, cells. The spatial extent lysis, detachment, increased with...

We describe the integrated use of pulsed laser microbeam irradiation and microfluidic cell culture methods to examine dynamics axonal injury regeneration in vitro. Microfabrication are used place high purity dissociated central nervous system neurons specific regions that allow axons interact with permissive inhibitory substrates. Acute neuron bundles is produced via delivery single 180 ps duration, λ = 532 nm pulses. Laser pulse energies 400 nJ 800 produce partial complete transection...

Starting from the radiative transport equation we derive scaling relationships that enable a single Monte Carlo (MC) simulation to predict spatially- and temporally-resolved reflectance homogeneous semi-infinite media with arbitrary scattering absorption coefficients. This derivation shows rigorous application of this (sMC) approach requires rescaling be done individually for each photon biography. We examine accuracy sMC method when processing simulations on an individual basis also...

The <i>Journal of Biomedical Optics</i> (JBO) is a Gold Open Access journal that publishes peer-reviewed papers on the use novel optical systems and techniques for improved health care biomedical research.

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