Applying laser pulse stretching technique on photoacoustic imaging for efficiently delivering laser energy

Tianheng Wang; Patrick D. Kumavor; Quing Zhu

doi:10.1117/12.913469

23 February 2012 Applying laser pulse stretching technique on photoacoustic imaging for efficiently delivering laser energy

Tianheng Wang, Patrick D. Kumavor, Quing Zhu

Author Affiliations +

Proceedings Volume 8223, Photons Plus Ultrasound: Imaging and Sensing 2012; 822347 (2012) https://doi.org/10.1117/12.913469
Event: SPIE BiOS, 2012, San Francisco, California, United States

Abstract

High-energy and short-duration outputs from lasers are desirable to improve the photoacoustic image quality when imaging deeply-seated lesions. In many clinical applications, optical fibers are used to couple the high-energy laser pulse to tissue. These high peak intensity pulses can damage an optical fiber input face if the damage threshold is exceeded. It is necessary to reduce the peak intensity to minimize the fiber damage and to delivery sufficient light for imaging. In this paper, a laser-pulse-stretching technique is introduced to reduce the peak intensity of laser pulses. To demonstrate the technique, an initial 17ns pulse was stretched to 37ns by a ring-cavity laser-pulse-stretching system, and the laser peak power reduced to 42%. The stretched pulse increased the fiber damage threshold by 1.5-fold. Three ultrasound transducers centered at 1.3MHz, 3.5MHz, 6MHz frequencies were simulated and the results showed that the photoacoustic signal of 0.5mm-diameter target obtained with 37ns pulse was about 98%, 91% and 80% respectively using the same energy as with the 17ns pulse. Simulations were validated using a broadband hydrophone. Quantitative comparisons of photoacoustic images obtained with three corresponding ultrasound transducers showed that the image quality was not affected by stretching the pulse.

Citation Download Citation

Tianheng Wang, Patrick D. Kumavor, and Quing Zhu "Applying laser pulse stretching technique on photoacoustic imaging for efficiently delivering laser energy", Proc. SPIE 8223, Photons Plus Ultrasound: Imaging and Sensing 2012, 822347 (23 February 2012); https://doi.org/10.1117/12.913469

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