THE VANCITTERT-ZERNIKE THEOREM IN PULSE ECHO MEASUREMENTS
THE VANCITTERT-ZERNIKE THEOREM IN PULSE ECHO MEASUREMENTS
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DOI：
10.1121/1.401867
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发表时间：
1991-11-01
影响因子：
2.4
通讯作者：
FINK, M
中科院分区：
文献类型：
--
作者：
MALLART, R;FINK, M
统计光学的经典定理，van Cittert-Zernike 定理，被推广到脉冲回波超声。该定理充分描述了非相干源产生的场的空间涨落（空间协方差）的二阶统计量。当随机散射介质被声穿透时，它表现为非相干源。因此，van Cittert-Zernike 定理可以预测随机介质反向散射的压力场的空间协方差。结果表明，该空间协方差和入射能量图是傅立叶对。在聚焦照明的情况下，反向散射压力场的空间协方差与发射孔径函数的自相关性成正比。这与频率和 F/数无关。使用线性阵列获得的实验结果与理论预期非常吻合。讨论了该定理在散斑减少和非均匀介质聚焦中的含义。
A classical theorem of statistical optics, the van Cittert-Zernike theorem, is generalized to pulse echo ultrasound. This theorem fully describes the second-order statistics of the spatial fluctuations (the spatial covariance) of the field produced by an incoherent source. As a random scattering medium is insonified, it behaves as an incoherent source. The van Cittert-Zernike theorem can thus predict the spatial covariance of the pressure field backscattered by a random medium. It is shown that this spatial covariance and the incident energy diagram are Fourier pairs. In the case of a focused illumination, the spatial covariance of the backscattered pressure field is proportional to the autocorrelation of the transmitting aperture function. This is independent of frequency and of F/number. Experimental results obtained with a linear array are in good agreement with theoretical expectations. The implications of this theorem in speckle reduction and in focusing in nonhomogenous media are discussed.