光相干层析成像中的散斑

由于光相干层析成像中测量的干涉信号空间频带有限 ,因此会产生散斑。在高散射的生物组织图像中 ,散斑具有双重身份 ,即作为噪声源和作为组织微结构的信号载体。本文的前半部分对于光相干层析成像中散斑的产生原因、统计特性以及分类作了综述。通过采样束的相位和振幅扰动可以定义信号载体散斑和信号降低散斑。本文的后半部分讨论了减少散斑的 4种方法 :偏振合成法、空间合成法、频率合成法和数字信号处理方法 ,并且通过举例对每一种方法的有效性作了简单的分析。最后 ,文章提出了需进一步研究的问题

Speckle in optical coherence tomography

Speckle arises as a natural consequence of the limited spatial frequency bandwidth of the interference signals measured in optical coherence tomography(OCT).In images of highly scattering biological tissues,speckle has a dual role as a source of noise and as a source of carrier of information about tissue microstructure.The first half of this paper provides an overview of the origin,statistical properties,and classification of speckle in OCT.The concepts of signal carrying and signal degrading speckle are defined in terms of the phase and amplitude disturbances of the sample beam.In the remaining half of the paper,four speckle reduction methods polarization diversity,spatial compounding,frequency compounding and digital signal processing are discussed and the potential effectiveness of each method is analyzed briefly with the aid of examples.Finally,remaining problems that merit further research are suggested.