Computer-generated holography enables high-uniformity, high-efficiency depth-of-focus extension in endoscopic OCT

TL;DR

This paper presents a novel computer-generated holography technique that extends the depth of focus in endoscopic OCT, enabling high-uniformity imaging without additional lenses, through direct fiber facet fabrication.

Contribution

It introduces a multi-level diffractive optics method using CGH for DOF extension in endoscopic OCT, fabricated directly on fiber tips with femtosecond laser 3D printing.

Findings

Numerical simulations confirm improved DOF and uniformity.

Beam measurements validate the holographic approach.

Imaging results demonstrate enhanced endoscopic OCT performance.

Abstract

Fiber-form optics extends the high-resolution tomographic imaging capabilities of Optical Coherence Tomography (OCT) to the inside of the human body, i.e., endoscopic OCT. However, it still faces challenges due to the trade-off between probe size, resolution, and Depth Of Focus (DOF). Here we introduce a method for extending the DOF in endoscopic OCT with high uniformity and efficiency. On the basis of multi-level diffractive optics, we leverage the multi-dimensional light field modulation capabilities of Computer-Generated Holography (CGH), to achieve precise control of the intensity distribution of the off-axis portion of the OCT probe light. Our method eliminates the need for an objective lens, allowing for direct fabrication at the distal facet of a single-mode fiber using femtosecond laser two-photon 3D printing. The superiority of our method has been verified through numerical simulation, beam measurement, and imaging results obtained with our home-built endoscopic OCT system.