Underwood H R, Burdette E C, Ocheltree K B, Magin R L
Bioacoustics Research Laboratory, University of Illinois, Urbana 61801.
Int J Hyperthermia. 1987 May-Jun;3(3):257-67. doi: 10.3109/02656738709140392.
Acoustic field patterns from a planar multi-element ultrasonic applicator were determined experimentally and compared with theory. Measurements were obtained from square arrays of 4 and 16 elements. The acoustic fields produced by various configurations of individual square elements (3.6 cm X 3.6 cm) driven at 1 MHz were measured in water. Transverse and axial scans paths were used to characterize the acoustic beam for different aperture sizes and individual element excitations. Unequal power excitation of adjacent elements produced multiple peaked acoustic intensity patterns. While a simple theoretical model was not able to account for all the experimentally determined transverse and axial field patterns, a model including mechanical damping improved the agreement between theory and experiment. However, less ripple in the axial pattern was measured than predicted by either theoretical model. The ability of the applicator to generate acoustic field patterns suitable for local tissue heating was demonstrated by an experimental study in dog thigh muscle.
通过实验确定了平面多阵元超声换能器的声场模式，并与理论进行了比较。测量是从4个和16个阵元的方形阵列获得的。在水中测量了由单个方形阵元（3.6厘米×3.6厘米）在1兆赫兹驱动下的各种配置所产生的声场。使用横向和轴向扫描路径来表征不同孔径尺寸和单个阵元激励下的声束。相邻阵元的不等功率激励产生了多个峰值声强模式。虽然一个简单的理论模型无法解释所有实验确定的横向和轴向场模式，但一个包含机械阻尼的模型改善了理论与实验之间的一致性。然而，测量到的轴向模式中的纹波比任何一个理论模型预测的都要少。在犬大腿肌肉中的一项实验研究证明了该换能器产生适合局部组织加热的声场模式的能力。
