Axially-shifted pattern illumination for macroscale turbidity suppression and virtual volumetric confocal imaging without axial scanning

TL;DR

This paper introduces axially-shifted pattern illumination (asPI), a method for virtual volumetric confocal imaging that eliminates the need for axial scanning by projecting tilted illumination patterns, enabling rapid 3D imaging in challenging environments.

Contribution

The novel asPI technique allows 3D confocal imaging without axial scanning by shifting illumination patterns laterally at different depths, significantly increasing imaging speed and robustness.

Findings

Achieved virtual confocal imaging in ~1 second.

Demonstrated imaging through diffusing layers and underwater environments.

Reached a throughput of 420 megapixels per second.

Abstract

Structured illumination has been widely used for optical sectioning and 3D surface recovery. In a typical implementation, multiple images under non-uniform pattern illumination are used to recover a single object section. Axial scanning of the sample or the objective lens is needed for acquiring the 3D volumetric data. Here we demonstrate the use of axially-shifted pattern illumination (asPI) for virtual volumetric confocal imaging without axial scanning. In the reported approach, we project illumination patterns at a tilted angle with respect to the detection optics. As such, the illumination patterns shift laterally at different z sections and the sample information at different z-sections can be recovered based on the captured 2D images. We demonstrate the reported approach for virtual confocal imaging through a diffusing layer and underwater 3D imaging through diluted milk. We show that we can acquire the entire confocal volume in ~1s with a throughput of 420 megapixels per second. Our approach may provide new insights for developing confocal light ranging and detection systems in degraded visual environments.