Improvement of scattering suppression effect of time-reversal propagation using digital phaseconjugate light
Improvement of scattering suppression effect of time-reversal propagation using digital phaseconjugate light
复制标题
利用数字相位共轭光提高时间反转传播的散射抑制效果
DOI：
10.1117/12.2505213
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Shimizu Koichi
中科院分区：
文献类型：
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作者：
Toda Sogo;Kato Yuji;Kudo Nobuki;Shimizu Koichi
混浊介质中的强散射是动物体内光学成像和测量的一个严重困难。因此，在生物医学光学的许多应用中，抑制散射效应是至关重要的。在动物体的光学透照成像中，这种效应表现为图像的强烈模糊。这种模糊造成了一个根本性的重要困难，限制了透照成像的实际应用。因此，我们试图利用相位共轭光的时间反转能力来抑制散射效应。在我们之前的研究中，我们构建了一个数字系统，以产生不仅具有共轭相位而且具有与非散射信号光相同强度分布的光。利用相位共轭光的时间反转传播特性，我们可以从模糊图像中恢复出入射光的图案。与只含相位信息的情况相比，我们发现，加入强度信息大大提高了时间反演原理的散射抑制能力。然而，我们的初步研究表明，这种能力是有效的，只有与光学距离OD小于1的散射介质。本报告描述了我们的测量系统的改进，使散射抑制与OD大于1的混浊介质使用具有较长的相干长度的光源。散射抑制是有效的0.4-1.0 lp/mm的空间频率通过散射介质高达OD=1.8。
Strong scattering in turbid medium is a severe difficulty for optical imaging and measurement in an animal body. Therefore, the suppression of scattering effect is crucially important in many applications of biomedical optics. In the optical transillumination imaging of an animal body, this effect appears as strong blurring of the image. This blurring poses a fundamentally important difficulty restricting the practical application of transillumination imaging. Therefore, we have attempted to suppress scattering effect using the time-reversal ability of phase-conjugate light. For our previous study, we constructed a digital system to generate light not only with conjugated phase but also with the same intensity distribution as non-scattered signal light. Using this system, we were able to restore the pattern of incident light from the blurred image because of time-reversal propagation of the phase-conjugate light. In comparison to a case with phase information only, we found that addition of the intensity information greatly improves the scattering suppression capability of the time-reversal principle. However, our pilot study showed this ability was valid only for the scattering medium with the optical distance OD less than 1. This report describes the improvement of our measurement system to make the scattering suppression possible for turbid media with OD of more than 1 using a light source with a longer coherence length. Scattering suppression was effective for spatial frequencies of 0.4–1.0 lp/mm through the scattering medium up to OD=1.8.