景深扩展型光控可变焦光纤探针设计及在血管内OCT的应用研究

The endoscopic optical coherence tomography (OCT), which is combined by optical coherence tomography and optical probe, presents advantages of high longitudinal resolution, flexibility and miniaturization structure. It provides a new strategy for interventional diagnosis and interventional therapy. However, the depth of focus and transverse resolution depended on OCT fiber probes are two constraining parameters. Therefore, the realization of high transverse resolution imaging could result in the reduction in the effective imaging range. In this project, we research on the design and application in intravascular OCT of light-controlled focus-tunable fiber probe with extended depth of focus. By establishing a dynamic mathematical model, the relationship between the characteristic parameters and the structure composition as well as structure parameters of the focus-tunable fiber probe is clarified. Based on changing the structural parameters of the fiber probe through pump light, two light-controlled focus-tunable fiber probes with different structures are realized. Finally, by adjusting the power of the pump light to achieve the focus spot scanning in the depth direction of the vessel wall and using image reconstruction technology, high-resolution intravascular OCT imaging with extended depth of focus is achieved. This project not only expands the research on OCT devices, but also provides a novel access to achieve high-quality OCT endoscopic imaging

将光纤探针与光学相干层析成像（Optical coherence tomography, OCT）结合的内窥OCT兼具了OCT高纵向分辨率和光纤结构柔性、微型化的特点，为介入医学提供了新的诊疗方式。然而，由光纤探针决定的横向分辨率和景深是一对相互制约的参数，高横向分辨率的实现，降低了有效成像范围。本项目针对景深扩展型光控可变焦光纤探针设计及在血管内OCT的应用进行研究。通过建立动态数学模型，明晰可变焦光纤探针特征参数与结构组成及结构参数之间的关系。以光控改变探针结构参数为出发点，实现两种结构不同的光控可变焦光纤探针制备。最终，通过调节泵浦光能量实现焦点光斑在血管壁深度方向上的扫描，结合图像重组技术实现超出景深范围的高分辨率血管内OCT成像。本项目不仅丰富了OCT的器件研究，更为高质量OCT内窥成像提供了新的技术手段。

为了全面准确地反映血管的病理学特点，临床应用对血管成像技术提出了高空间分辨率层析式成像的要求。基于光纤探针的内窥式光学相干层析成像（Optical coherence tomography, OCT）为高质量血管成像提供了新的技术手段。研究新型高性能的OCT 光纤探针，对于进一步提高血管内OCT 的成像质量，以及推动内窥OCT 技术在生物医学领域的发展等方面具有重要的科学和现实意义。.本项目按原定计划开展了研究，并取得了预期的研究成果：（1）利用矩阵光学算法，对不同结构的光纤探针建立对应的数学模型，探明了光纤探针的特征参数与结构组成以及结构参数之间的关系；（2）提出了两种不同的微结构焦点可调式光纤探针。实验验证当温度改变引起探针扩束长度变化时，焦距可由1835.37μm变化至1650.24μm，理论验证了当泵浦光造成温度改变并引起微结构光纤模场面积变化时，焦距由62.7300μm变化至64.4541μm；(3) 将可变焦探针的焦点调节于样品不同深度处得到的图像进行整合，实现了超出景深范围的重组成像；完成了基于光学相干弹性成像的角膜固有频率弹性测量.

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