采用中心波长为840 nm,带宽为50 nm的宽带近红外光源,基于低相干干涉原理和快速扫描延迟线(RSOD)相位调制的外差探测方法,建立了单模光纤型光学相干层析(OCT)成像系统,依此获得自然状态下活体组织的二维纵向截面成像图像。实验结果表明,系统的轴向分辨率为6.7 μm,接近理论分辨率,纵向成像范围高达3 mm,横向分辨率为4.7 μm; 入射到样品的光功率低于300 μW,系统探测灵敏度大于88 dB。在保证样品入射光功率相同的情况下,与中心波长为1310 nm,带宽为65 nm的单模光纤型光学相干层析成像系统对含水量高的新鲜橙子果肉的成像结果进行对比,验证了该系统用于眼后段组织成像的优越性,给出了活体动物视网膜的成像结果。

A newly developed single-mode fiber-designed optical coherence tomography (OCT) system is built based on low coherence interferometry and optical heterodyne detection. A broadband infrared optical source centered at 840 nm with a bandwidth of 50 nm is used as the system source. A stable high carrier is generated by Fourier-domain rapid scanning optical delay line (RSOD) as phase modulator. With this developed system, two-dimensional (2D) cross sectional images of tissues in vivo are reconstructed. The experiment results indicate that the system has an axial resolution of 6.7 μm, approaching the ideal resolution, and transversal resolution of 4.7 μm in air. The depth imaging range is above 3 mm in air. Although less than 300 μW optical power is incident on the sample, the system sensitivity is above 88 dB. With the same incident power on the sample, an image of the same sample (fresh orange) with a 1310 nm OCT system is also provided. The qualitative comparisons between the two system at different central wavelengths demonstrate the impressive potential of 840 nm OCT system to perform eye posterior structure imaging. The image of the animal retina in vivo is presented.