Kübler Johannes, Zoutenbier Vincent S, Buist Gijs, Fischer Jörg, Amelink Arjen, de Boer Johannes F
LaserLaB, Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, The Netherlands.
Heidelberg Engineering GmbH, Heidelberg, Germany.
Biomed Opt Express. 2023 Sep 18;14(10):5282-5297. doi: 10.1364/BOE.498459. eCollection 2023 Oct 1.
Optical coherence tomography (OCT) is conventionally used for structural imaging of tissue. Calibrating the intensity values of OCT images can give information on the tissue's inherent optical properties, such as the attenuation coefficient, which can provide an additional parameter to quantify possible pathological changes. To obtain calibrated intensity values, the focus position and Rayleigh length of the incident beam need to be known. We explore the feasibility of extracting the focus position from an OCT scan acquired with a single focus setting using the chromatic aberration of the system. The chromatic focal shift of an OCT system is exploited to achieve different focus positions for sub-spectrum reconstructed OCT images. The ratios of these images are used to estimate the focus position. Reconstruction of a high-resolution B-scan from coherent addition of sub-spectrum confocal function corrected B-scans and subsequent high-resolution OCT attenuation coefficient imaging is demonstrated. Furthermore, we introduce a method to experimentally determine the chromatic focal shifts of an OCT system in phantoms and an human retina. These shifts are compared to the theoretically expected shifts calculated with ray tracing.
光学相干断层扫描（OCT）传统上用于组织的结构成像。校准OCT图像的强度值可以提供有关组织固有光学特性的信息，例如衰减系数，这可以提供一个额外的参数来量化可能的病理变化。为了获得校准后的强度值，需要知道入射光束的焦点位置和瑞利长度。我们探索了利用系统的色差从单焦点设置采集的OCT扫描中提取焦点位置的可行性。利用OCT系统的色焦移为子光谱重建的OCT图像实现不同的焦点位置。这些图像的比率用于估计焦点位置。展示了通过子光谱共焦函数校正的B扫描的相干相加重建高分辨率B扫描以及随后的高分辨率OCT衰减系数成像。此外，我们介绍了一种通过实验确定OCT系统在体模和人视网膜中的色焦移的方法。将这些偏移与通过光线追踪计算的理论预期偏移进行比较。
