Marschall Sebastian, Pedersen Christian, Andersen Peter E
DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark , Frederiksborgvej 399, 4000 Roskilde, Denmark.
Biomed Opt Express. 2012 Jul 1;3(7):1620-31. doi: 10.1364/BOE.3.001620. Epub 2012 Jun 18.
Recently, the wavelength range around 1060 nm has become attractive for retinal imaging with optical coherence tomography (OCT), promising deep penetration into the retina and the choroid. The adjacent water absorption bands limit the useful bandwidth of broadband light sources, but until now, the actual limitation has not been quantified in detail. We have numerically investigated the impact of water absorption on the axial resolution and signal amplitude for a wide range of light source bandwidths and center wavelengths. Furthermore, we have calculated the sensitivity penalty for maintaining the optimal resolution by spectral shaping. As our results show, with currently available semiconductor-based light sources with up to 100-120 nm bandwidth centered close to 1060 nm, the resolution degradation caused by the water absorption spectrum is smaller than 10%, and it can be compensated by spectral shaping with negligible sensitivity penalty. With increasing bandwidth, the resolution degradation and signal attenuation become stronger, and the optimal operating point shifts towards shorter wavelengths. These relationships are important to take into account for the development of new broadband light sources for OCT.
最近，1060纳米左右的波长范围对于采用光学相干断层扫描（OCT）的视网膜成像变得具有吸引力，有望实现对视网膜和脉络膜的深度穿透。相邻的水吸收带限制了宽带光源的可用带宽，但到目前为止，实际限制尚未得到详细量化。我们已经对广泛的光源带宽和中心波长范围内水吸收对轴向分辨率和信号幅度的影响进行了数值研究。此外，我们还计算了通过光谱整形保持最佳分辨率时的灵敏度损失。正如我们的结果所示，对于目前可用的带宽高达100 - 120纳米、中心波长接近1060纳米的基于半导体的光源，水吸收光谱导致的分辨率下降小于10%，并且可以通过光谱整形进行补偿，灵敏度损失可忽略不计。随着带宽增加，分辨率下降和信号衰减变得更强，最佳工作点向更短波长偏移。这些关系对于开发用于OCT的新型宽带光源而言，是需要考虑的重要因素。
