부산대학교 도서관

The total focusing method (TFM) attracts much interest because of high image resolution and large dynamic range. However, the signal-to-noise ratio (SNR) of TFM is relatively low due to single-element emission. Especially in highly attenuating materials, the signal amplitude may be reduced with depth to a level lower than the electronic noise introduced by the signal acquisition system. Golay-coded excitation was introduced to overcome this problem, however, the double-excitations reduce the time resolution and may lead to negative decoding performance due to the relative change of scanning positions. In this work, the AB code conversion factor was used to realize the TFM imaging based on Golay-coded single-excitation which has a good performance as traditional Golay-coded excitation. A series of simulations and experiments were conducted to compare performance of TFM using un-coded excitation, Golay-coded excitation and modified Golay-coded excitation. TFM using modified Golay-coded excitation could overcome the disadvantages of double-excitation, and has approximately the same SNR gain as TFM using traditional one.