内窥式扫频光源光学相干层析系统的探头设计

Design of the Probe of Swept Source Optical Coherence Tomography for Endoscopic Imaging

利用自聚焦透镜和单模光纤搭建了基于光纤旋转连接器的内窥式扫频光源光学相干层析成像系统.利用Zemax模拟了内窥探头的光学性能,分析了光纤到自聚焦透镜的距离和自聚焦透镜节距对探头性能参量的影响.在综合考虑元器件成本以及成像要求后,选择无需定制,节距为0.24Pitch的自聚焦透镜,确定光纤与自聚焦透镜之间的距离为0.7mm.经实验测得该系统的横向分辨率约为19.5μm,纵向分辨率约为9μm,工作距离约为7mm,成像深度为6.2mm(空气中),与理论值接近.为了验证该系统对生物组织的成像性能,利用该系统对猪食道进行离体成像,重建后的层析图中可以明显地观察到猪肠道的表皮层和固有层.测量系统的各项成像性能参量以及对生物组织的成像性能表明该探头在内窥成像中是可行的.

A swept source endoscopic optical coherence tomography system was designed with the grinlens,single mode fiber and fiber optic rotary joint for endoscopic imaging.The effects of the pitch of the grin lens and the distance between the single mode fiber and the grin-lens on system performance were then analyzed with Zemax.The object distance of 0.7 mm was chosen according to the diameter of esophagus and the Pitch of 0.24 Pwas chosen according to the cost and the effects analyzed above.The measurement results shown that the axial resolution of the system is^9μm and the lateral resolution is^19.5μm with the imaging depth of 6mm in air.The working distance of the probe is about 7mm.The initial cross-sectional images of the intestinal tract of pig were presented to demonstrate the capability of the system for endoscopic applications.And all these results demonstrated that the probe designed is suitable for endoscopic imaging of esophagus.