The dual-pulse nonlinear photoacoustic technique is a recently developed technology based on temperature dependence of the Grüneisen parameter and involves consecutive excitations of biological tissue using two laser pulses with a short time delay. Here we review the principle of the technique and give a discussion about its technical aspects, including selection and combination of excitation laser wavelengths, determination of laser fluence, estimation of thermal relaxation function and probability of photoablation or cavitation. Comparisons between the dual-pulse technique and conventional photoacoustics as well as thermal photoacoustics are also presented. These investigations are supported by experimental results and will give a practical reference and guide for further developments of the technique.
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http://dx.doi.org/10.1364/BOE.6.002923 | DOI Listing |
In the paper, we present a qualitative analysis of the dual-pulse phase optical time domain reflectometry (phase-OTDR) response to uniform and nonuniform propagating fiber strain. It is found that on average over all realizations of scattering centers the response of the dual-pulse phase-OTDR is linear with respect to an external perturbation. Meanwhile, individual responses contain random phase jumps, which are an intrinsic property of phase-OTDR.
View Article and Find Full Text PDFA single-/dual-pulse repetition rate variable supercontinuum (SC) light source (SLS) with a peak wavelength of around 1.7 µm (SLS around 1.7 µm) is proposed and experimentally demonstrated.
View Article and Find Full Text PDFThe feasibility of diagnostic imaging and tissue characterization based on a new contrast realized by dual-pulse photoacoustic measurement was studied. Unlike current photoacoustic methods which are mostly focused on the measurement of tissue optical absorption, this contrast revealed by a dual-pulse laser excitation process takes advantage of the temperature dependence of the Grüneisen parameter of tissue. The first laser pulse heats the sample and causes a temperature rise in the target tissue, which leads to a change of the Grüneisen parameter and the amplitude of the photoacoustic signal from the second laser pulse.
View Article and Find Full Text PDFBiomed Opt Express
August 2015
Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
The dual-pulse nonlinear photoacoustic technique is a recently developed technology based on temperature dependence of the Grüneisen parameter and involves consecutive excitations of biological tissue using two laser pulses with a short time delay. Here we review the principle of the technique and give a discussion about its technical aspects, including selection and combination of excitation laser wavelengths, determination of laser fluence, estimation of thermal relaxation function and probability of photoablation or cavitation. Comparisons between the dual-pulse technique and conventional photoacoustics as well as thermal photoacoustics are also presented.
View Article and Find Full Text PDFNat Photonics
February 2015
Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130-4899.
Non-invasively focusing light into strongly scattering media, such as biological tissue, is highly desirable but challenging. Recently, ultrasonically guided wavefront shaping technologies have been developed to address this limitation. So far, the focusing resolution of most implementations has been limited by acoustic diffraction.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!