Dual wavelength laser diode excitation source for 2D photoacoustic imaging

Thomas J. Allen; Paul C. Beard

doi:10.1117/12.698651

27 February 2007 Dual wavelength laser diode excitation source for 2D photoacoustic imaging

Thomas J. Allen, Paul C. Beard

Proceedings Volume 6437, Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics; 64371U (2007) https://doi.org/10.1117/12.698651
Event: SPIE BiOS, 2007, San Jose, California, United States

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.

Citation Download Citation

Thomas J. Allen and Paul C. Beard "Dual wavelength laser diode excitation source for 2D photoacoustic imaging", Proc. SPIE 6437, Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 64371U (27 February 2007); https://doi.org/10.1117/12.698651

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