Opt Express. 2021 Jul 19;29(15):23083-23095. doi: 10.1364/OE.426235.
Microendoscopes based on optical fibres have recently come to the fore as promising candidates allowing in-vivo observations of otherwise inaccessible biological structures in animal models. Despite being still in its infancy, imaging can now be performed at the tip of a single multimode fibre, by relying on powerful holographic methods for light control. Fibre based endoscopy is commonly performed en face, resulting in possible damage of the specimen owing to the direct contact between the distal end of the probe and target. On this ground, we designed an all-fibre probe with an engineered termination that reduces compression and damage to the tissue under investigation upon probe insertion. The geometry of the termination brings the field of view to a plane parallel to the fibre's longitudinal direction, conveying the probe with off-axis imaging capabilities. We show that its focusing ability also benefits from a higher numerical aperture, resulting in imaging with increased spatial resolution. The effect of probe insertion was investigated inside a tissue phantom comprising fluorescent particles suspended in agarose gel, and a comparison was established between the novel side-view probe and the standard en face fibre probe. This new concept paves the way to significantly less invasive deep-tissue imaging.
基于光纤的微内窥镜最近成为有前途的候选者，能够在动物模型中对原本无法进入的生物结构进行体内观察。尽管仍处于起步阶段，但现在可以通过依赖强大的光控全息方法在单根多模光纤的尖端进行成像。基于纤维的内窥镜通常是面内成像，由于探头的远端与目标直接接触，因此可能会对标本造成损伤。基于这一点，我们设计了一种带有工程端的全光纤探头，该探头可减少探头插入时对被研究组织的压缩和损伤。该探头的终止端几何形状将视场带到与光纤纵向方向平行的平面上，从而实现了具有离轴成像能力的探头。我们证明，其聚焦能力也得益于更高的数值孔径，从而实现了具有更高空间分辨率的成像。我们在包含琼脂糖凝胶中悬浮的荧光粒子的组织体模内研究了探头插入的效果，并在新型侧视探头和标准面内光纤探头之间建立了比较。这个新概念为实现侵入性更小的深层组织成像铺平了道路。
