光学相干断层扫描（英文: Optical coherence tomography，简称OCT）是一种光学信号获取与处理的方式。它可以对光学散射介质如生物组织等进行扫描，获得的三维图像分辨率可以达到微米级。光学相干断层扫描技术利用了光的干涉原理，通常采用近红外光进行拍照。由于选取的光线波长较长，可以穿过扫描介质的一定深度。另一种类似的技术，共焦显微技术，穿过样品的深度不如光学相干断层扫描。

光学相干断层扫描使用的光源包括超辐射发光二极管与超短脉冲激光。根据光源性质的不同，这种扫描方式甚至可以达到亚微米级的分辨率，这时需要光源的频谱非常宽，波长的变化范围在100纳米左右。

Optical coherence tomography (OCT) is an established medical imaging technique that uses light to capture micrometer-resolution, three-dimensional images from within optical scattering media (e.g., biological tissue). Optical coherence tomography is based on low-coherence interferometry, typically employing near-infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium. Confocal microscopy, another optical technique, typically penetrates less deeply into the sample but with higher resolution.