3D-printed axicon enables extended depth-of-focus intravascular optical coherence tomography

TL;DR

This paper introduces a novel 3D-printed axicon-based endoscopic probe that achieves high-resolution, extended depth-of-focus intravascular optical coherence tomography, overcoming previous aberration limitations with a micro 3D-printing fabrication method.

Contribution

The authors develop a freeform beam-shaping endoscopic probe fabricated via two-photon direct laser writing, enabling diffraction-limited resolution over a large depth of focus in intravascular imaging.

Findings

Achieves ~8-micron resolution with >0.8 mm DOF at 1310 nm

Fabricated with a single step directly on optical fiber

Demonstrated in vivo in pigs and ex vivo in human arteries

Abstract

A fundamental challenge in endoscopy is how to fabricate a small fiber-optic probe that can achieve comparable function to probes with large, complicated optics (e.g., high resolution and extended depth of focus). To achieve high resolution over an extended depth of focus (DOF), the application of needle-like beams has been proposed. However, existing methods using miniaturized needle beam designs fail to adequately correct astigmatism and other monochromatic aberrations, limiting the resolution of at least one axis. Here, we describe a novel approach to realize freeform beam-shaping endoscopic probes via two-photon direct laser writing, also known as micro 3D-printing. We present a design achieving approximately 8-micron resolution with a DOF of >0.8 mm at a central wavelength of 1310 nm. The probe has a diameter of 0.25 mm (without the catheter sheaths) and is fabricated using a single printing step directly on the optical fiber. We demonstrate our device in intravascular imaging of living atherosclerotic pigs at multiple time points, as well as human arteries with plaques ex vivo. This is the first step to enable beam-tailoring endoscopic probes which achieve diffraction-limited resolution over a large DOF.