Experimental optimization of lensless digital holographic microscopy with rotating diffuser-based coherent noise...

High-quality imaging in laser-based systems often suffers from significant coherent noise. This interference creates speckle patterns that obscure fine details in captured data. Prior research has shown that these artifacts limit the reliability of digital holographic reconstruction. No prior work had resolved how to effectively mitigate these issues in lensless configurations. That uncertainty drove the need for a hardware-based solution to improve signal clarity. Previous attempts to address this problem often compromised the simplicity of the imaging device. This gap motivated the development of a strategy that maintains a compact design. The current study addresses these limitations by integrating a specific optical component to manage coherence.

The primary aim of this study is to optimize lensless digital holographic microscopy by mitigating coherent noise artifacts. These artifacts, such as speckle noise and parasitic fringes, often degrade the quality of captured images. The researchers seek to implement a rotating diffuser to introduce partial spatial coherence into the system. This approach intends to preserve the high temporal coherence required for accurate in-line hologram reconstruction. The team also aims to perform a comprehensive hardware optimization to ensure the device remains compact. They focus on balancing noise reduction with the maintenance of optimal spatial resolution. By validating this method with complex biological samples, the authors address the need for reliable imaging tools. This work ultimately explores how to improve signal-to-noise ratios in stain-free biomedical screening applications.

The research team performed a systematic hardware optimization using four light sources and four cameras. They tested three distinct optical magnifications by adjusting the distance between the camera and the sample. This review approach focused on quantifying numerical amplitude and phase reconstructions of standard test targets. The investigators calculated the standard deviation to determine the specific noise factor reduction. They also evaluated information throughput to ensure that spatial resolution remained consistent throughout the process. Following these tests, they implemented a rotating diffuser to modulate spatial coherence. This component was integrated into the existing device to preserve temporal coherence during data acquisition. The final setup was validated by imaging both technical targets and a thick mouse brain tissue slice.

The proposed method successfully reduced coherent noise by up to 50% during imaging experiments. This physical minimization of artifacts occurred while maintaining optimal spatial resolution for both phase and amplitude data. The researchers corroborated these results using technical test targets and a 60 µm thick mouse brain tissue slice. Their quantitative assessment confirmed that the rotating diffuser preserves the necessary temporal coherence for credible reconstruction. The team observed that the device remained compact and straightforward despite the added optical component. Signal-to-noise ratios improved significantly compared to standard configurations without the diffuser. The findings show that speckle noise, which often mimics biological features, is effectively suppressed. This outcome supports the use of the system for reliable, high-throughput biomedical screening applications.

The authors demonstrate that integrating a rotating diffuser effectively minimizes coherent noise by up to fifty percent. This implementation preserves the spatial resolution required for accurate phase and amplitude imaging. The researchers suggest that this approach enhances the credibility of in-line hologram reconstruction. Their findings indicate that the method maintains the compact nature of the original imaging device. The team highlights that removing speckle artifacts is vital for reliable biomedical inference. They note that these patterns can otherwise mimic valid biological features during analysis. The study proposes that combining this noise reduction with a large field-of-view supports high-throughput screening applications. Finally, the authors conclude that their technique offers a robust solution for stain-free imaging of complex tissue samples.