# 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.

## Key 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.

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Source: https://tomesphere.com/paper/1812.06125