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. Author manuscript; available in PMC: 2012 Aug 1.
Published in final edited form as: Ultrasound Med Biol. 2011 Jun 8;37(8):1259–1270. doi: 10.1016/j.ultrasmedbio.2011.04.019

Figure 1.

Figure 1

Plots of the normalized acoustic pressure distribution for the 532 kHz unfocused transducer. A rubber absorber with a circular aperture was used to move the Fresnel distance to approximately 2 cm away from the rubber. This aperture enabled the transducer to be operated within the animal MRI system with the brain in this region and not in the near field. (A): Map of the pressure distribution perpendicular to the beam direction at this depth. Contours at 10 to 50% of the peak pressure amplitude are shown. (B): Map along the direction of beam propagation. (C) and (D): Pressure distributions perpendicular and parallel to the beam direction. Lines through the peak and at ±0.7 and 1.3 mm away are shown.