时间反转TR（time-reversal）具有空-时同步聚焦和空间的超分辨率聚焦特性。基于已有随机介质中TR的理论方法，进一步分析随机介质对TR聚焦成像的影响。通过仿真实验，探讨不同光学厚度条件下阵列稀疏化、随机介质位置及随机介质参数对TR聚焦效果的影响。结果表明，随机介质中的多次散射可以提高TR的成像和聚焦能力，达到超分辨的特性。同时，在随机介质场景下，TR成像对所讨论的多种情况体现出良好的容忍度和适应性。
Time-reversal (TR) has the advantages of space-time focusing and super resolution. In this work, the effects of random media on TR focusing and imaging are analyzed. The simulation experiments are carried out to investigate the performance of TR focusing and imaging, in cases of different array sparsities, varying optical depths, different locations, and different albedos of the random medium. Results indicate that the multipath scattering within the random media enhances the super resolution capability of TR imaging. Also, the imaging performance of TR focusing shows considerable adaptability to various random media parameters and array sparsities.
[1] Lerosey G, De Rosny J, Tourin A, et al. Time reversal of electromagnetic waves[J]. Physical Review Letters, 2004, 92(19):193904.
[2] Lerosey G, De Rosny J, Tourin A, et al. Time reversal of electromagnetic waves and telecommunication[J]. Radio Science, 2005, 40(6):RS6S12.
[3] Fink M. Time reversed acoustics[J]. Physics Today, 1997, 50(3):34-40.
[4] Borcea L, Papanicolaou G, Tsogka C, et al. Imaging and time reversal in random media[J]. Inverse Problems, 2002, 18(5):1247.
[5] Derode A, Tourin A, Fink M. Random multiple scattering of ultrasound. I. Coherent and ballistic waves[J]. Physical Review E, 2001, 64(3):036605.
[6] Derode A, Tourin A, Fink M. Random multiple scattering of ultrasound. Ⅱ. Is time reversal a self-averaging process[J]. Physical Review E, 2001, 64(3):036606.
[7] Blomgren P, Papanicolaou G, Zhao H. Super-resolution in time-reversal acoustics[J]. The Journal of the Acoustical Society of America, 2002, 111(1):230-248.
[8] Lerosey G, De Rosny J, Tourin A, et al. Time reversal of electromagnetic waves[J]. Physical Review Letters, 2004, 92(19):193904.
[9] Liu D, Vasudevan S, Krolik J, et al. Electromagnetic time-reversal source localization in changing media:Experiment and analysis[J]. IEEE Transactions on Antennas and Propagation, 2007, 55(2):344-354.
[10] Ishimaru A, Jaruwatanadilok S, Kuga Y. Time reversal effects in random scattering media on superresolution, shower curtain effects, and backscattering enhancement[J]. Radio Science, 2007, 42(42):507-530.
[11] Ishimaru A, Jaruwatanadilok S, Kuga Y. Multiple scattering effects on the radar cross section (RCS) of objects in a random medium including back-scattering enhancement and shower curtain effects[J]. Waves in Random Media, 2004, 14(4):499-512.
[12] Ishimaru A, Jaruwatanadilok S, Kuga Y. Short pulse detection and imaging of objects behind obscuring random layers[J]. Waves in Random and Complex Media, 2006, 16(4):509-520.
[13] Ishimaru A, Jaruwatanadilok S, Kuga Y. Imaging of a target through random media using a short-pulse focused beam[J]. IEEE Transactions on Antennas and Propagation, 2007, 55(6):1622-1629.
[14] Liu D, Vasudevan S, Krolik J, et al. Electromagnetic time-reversal source localization in changing media:Experiment and analysis[J]. IEEE Transactions on Antennas and Propagation, 2007, 55(2):344-354.
[15] Goodman J W, Narducci L M. Statistical Optics[J]. Physics Today, 1986, 39(10):126-126.
[16] Ishimaru A. Wave propagation and scattering in random media[M]. New York:Academic Press, 1978.
