Tunable Dynamic Speckle Generation for Random Illumination Microscopy

TL;DR

This paper introduces a low-cost, tunable liquid crystal device for generating dynamic speckle patterns, enhancing random illumination microscopy by improving resolution and optical sectioning while reducing complexity and cost.

Contribution

The authors develop a zwitterion-doped liquid crystal device capable of producing high-contrast, tunable speckle patterns, offering a simpler and more affordable alternative to existing pattern generation methods.

Findings

Achieved 2 micron axial resolution in tissue imaging.

Realized a 1.5-fold increase in lateral spatial resolution.

Enabled optical sectioning with tunable decorrelation times.

Abstract

Speckled illumination enhances widefield fluorescence microscopy by enabling optical sectioning and super resolution. In random illumination microscopy, sequences of speckled illumination patterns are used to excite fluorescent samples and images are reconstructed based on a statistical analysis of the intensity fluctuations. Although random illumination microscopy has been shown to give excellent performance, its widespread implementation is hindered by the high cost and complexity of the generation of suitable speckled illumination patterns, which is achieved using digital micro-mirror devices or spatial light modulators. Here, we present a zwitterion-doped liquid crystal (LC) device capable of generating independent, high-contrast speckle patterns with a tunable decorrelation time in the 0.1 s to 0.1 ms range under visible laser illumination. This LC-based dynamic speckle generator is applied to widefield random illumination fluorescence microscopy of tissue and cell samples, where it enables optical sectioning with a 2 micron axial resolution, and a 1.5-fold improvement in lateral spatial resolution. Owing to its low cost and simplicity, this LC speckle generator offers an attractive alternative to digital micro-mirror and spatial light modulator devices for implementing widefield random illumination microscopy.