相衬光学相干弹性成像的超分辨应变测量

Super-resolution strain measurement in phase-contrast optical coherence elastography

相衬光学相干弹性成像的相位分辨率受限于系统的光源带宽,导致层析应变成像质量低。这严重制约了相衬光学相干弹性成像的实际应用与发展。为此,本文提出一种基于数据驱动的超分辨应变测量方法,以解决相位分辨率受限下的应变重构困难问题。首先,根据相衬光学相干弹性成像原理,搭建了层析应变测量模型,用于获取网络训练所需的数据集,解决实际测量过程中超分辨应变标签难以获取的问题。其次,构建深度卷积神经网络,通过带有层析分辨率受限特点的数据驱动方式,让网络学习低分辨相位与高分辨应变之间的映射关系,从而实现相衬光学相干弹性成像的超分辨应变测量。最后,采用数值验证和压缩变形加载实验对本文方法的性能进行验证。实验结果表明本文方法在窄带宽输出下能重构出宽带宽的应变测量效果,并且其信噪比相比于矢量方法和传统应变计算深度神经网络,分别提高了18.4 dB和1.45 dB。本文方法可以突破系统光源的带宽限制,在低分辨相位输入条件下实现超分辨应变测量,从而加快相衬光学相干弹性成像在力学性能表征、内部早期损伤探测等方面的应用前景。

The resolution of phase-contrast optical coherence elastography(PC-OCE)is constrained by the bandwidth of the system′s light source,leading to poor quality in tomographic strain imaging.This limitation significantly hinders the practical implementation and advancement of PC-OCE.This study introduced a data-driven super-resolution strain measurement approach to tackle the challenge of strain reconstruction under restricted phase resolution.Firstly,according to the principle of PC-OCE,a simulation measurement model was built to obtain the required data set,which solved the problem that was is difficult to obtain the ground truth in the real measurement process.Secondly,a deep neural network was used to learn the mapping relationship between low-resolution phase and high-resolution strain through a data-driven manner,realizing the super-resolution measurement of strain.Finally,numerical validation and com pression deformation loading experiments were employed to validate the efficacy of the method introduced in this study.The experimental results demonstrate that the approach presented in this study can reconstruct the strain measurement outcomes across a wide bandwidth despite operating under a narrow bandwidth output.Furthermore,the signal-to-noise ratio is enhanced by 18.4 dB and 1.45 dB in comparison to the vector method and conventional deep neural network for strain calculation.The proposed method overcomes the bandwidth limitation of the system light source,enabling super-resolution strain measurement under low-resolution phase input conditions.This advancement enhances the potential applications of phase-contrast optical coherence elastography in characterizing mechanical performance,detecting early internal damage,and other related areas.