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Proceedings Paper

Dual wavelength laser diode excitation source for 2D photoacoustic imaging
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Paper Abstract

Photoacoustic methods can be used to make spatially resolved spectroscopic measurements of blood oxygenation when using a multiwavelength excitation source, such as an OPO system. Since these excitation sources are usually expensive and bulky, an alternative is to use laser diodes. A fibre coupled laser diode excitation system has been developed, providing two wavelengths, 850 and 905nm, each composed of 6 high peak power pulsed laser diodes. The system provided variable pulse durations (65-500ns) and repetition rates of up to 5KHz. The pulse energies delivered by the excitation system at 905nm and 850nm were measured to be 120&mgr;J and 80&mgr;J respectively for a 200ns pulse duration. To demonstrate the utility of the system, the excitation source was combined with an ultrasound detector to form a probe for in vivo single point measurements of superficial blood vessels. Changes in blood oxygenation and volume in the finger tip were monitored while making venous and arterial occlusions. To demonstrate the imaging capability of the excitation system, 2D photoacoustic images of a physiologically realistic phantom were obtained for a range of pulse durations using a cylindrical scanning system. The phantom was composed of cylindrical absorbing elements (&mgr;a=1mm^{-1}) of 2.7mm diameter, immersed in a 1% intralipid solution (&mgr;s=1mm^{-1}). This study demonstrated the potential use of laser diodes as an excitation source for photoacoustic imaging of superficial vascular structures.

Paper Details

Date Published: 27 February 2007
PDF: 9 pages
Proc. SPIE 6437, Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 64371U (27 February 2007); doi: 10.1117/12.698651
Show Author Affiliations
Thomas J. Allen, Univ. College London (United Kingdom)
Paul C. Beard, Univ. College London (United Kingdom)


Published in SPIE Proceedings Vol. 6437:
Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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