Challenges in Developing a Bessel-Beam Based Ultrafast Ablation Probe

With its elongated depth of focus, Bessel beams offer rapid and high aspect ratio ablation capability, in contrast to Gaussian beam counterparts. In this study, we summarize our efforts in design and characterization of a half-inch diameter probe comprising a hollow core photonics crystal fiber for ultrafast laser delivery, an aspherical lens to collimate the light exiting fiber output, an axicon to generate the Bessel beam, and a relay lens pair to establish a narrow main lobe for improved laser fluence. We discuss two main challenges in transferring the available laser energy to the target: i) fiber damage and ii) energy wasted at the Bessel side-lobes. Solutions that have been proposed in other bench top literary studies are revisited in terms of their practical and realistic adaptation within a probe for potential clinical use. With further development, the proposed Bessel-beam based probe can be targeted for minimally invasive in-vivo activation of follicles for the treatment of premature ovarian failure, potentially leading to shortened healing duration and improved patient comfort.