High-resolution long-working-distance reference-free holographic microscopy exploiting speckle-correlation scattering matrix

TL;DR

This paper introduces a novel lensless holographic microscopy technique that uses a scattering layer and speckle-correlation scattering matrix to achieve high-resolution imaging at long working distances without external reference beams.

Contribution

It presents a new lensless microscopy method combining speckle-correlation scattering matrix with scattering layers for high-resolution, long-distance imaging.

Findings

Achieved high-resolution imaging beyond conventional objectives.

Demonstrated lensless holography without external reference beams.

Validated method with microscopic sample imaging.

Abstract

Using conventional refraction-based optical lens, it is challenging to achieve both high-resolution imaging and long-working-distance condition. To increase the numerical aperture of a lens, the working distance should be compensated, and vice versa. Here we propose and demonstrate a new concept in optical microscopy that can achieve both high-resolution imaging and long-working-distance conditions by utilising a scattering layer instead of refractive optics. When light passes through a scattering layer, it creates a unique interference pattern. To retrieve the complex amplitude image from the interference pattern without introducing a reference beam, we utilised a speckle-correlation scattering matrix method. This property enables holographic microscopy without any lens or external reference beam. Importantly, the proposed method allows high-resolution imaging with a long working distance beyond what a conventional objective lens can achieve. As an experimental verification, we imaged various microscopic samples and compared their performance with off-axis digital holographic microscopy.