# Visible spectrum extended-focus optical coherence microscopy for label-free sub-cellular tomography

## TL;DR

This paper introduces visOCM, a novel extended-focus optical coherence microscopy technique that achieves near-isotropic submicron 3D resolution over a 40 μm depth using a broad super-continuum spectrum from visible to near-infrared wavelengths.

## Contribution

The paper presents a new extended-focus OCM method utilizing a super-continuum laser for high-resolution, label-free sub-cellular imaging over a significant depth.

## Key findings

- Achieves 0.7 μm axial and 0.4 μm lateral resolution.
- Maintains high resolution over 40 μm depth.
- Demonstrates effective imaging on cells and tissue samples.

## Abstract

We present a novel extended-focus optical coherence microscope (OCM) attaining 0.7 {\mu}m axial and 0.4 {\mu}m lateral resolution maintained over a depth of 40 {\mu}m, while preserving the advantages of Fourier domain OCM. Our method uses an ultra-broad spectrum from a super- continuum laser source. As the spectrum spans from near-infrared to visible wavelengths (240 nm in bandwidth), we call the method visOCM. The combination of such a broad spectrum with a high-NA objective creates an almost isotropic 3D submicron resolution. We analyze the imaging performance of visOCM on microbead samples and demonstrate its image quality on cell cultures and ex-vivo mouse brain tissue.