Super-Resolution by Structured Illumination: Digital Holographic Microscopy for Metrology of Nanomaterials

Digital holographic microscopy (DHM) resolution, constrained by the emission wavelength and numerical aperture, can be enhanced through structured illumination techniques. This article introduces a structured illumination microscopy method utilizing a speckle pattern generated by a Scotch tape diffuser to achieve super-resolution (SR) quantitative phase imaging. The SRAD-DIHM system (SR using alternating direction method of multipliers (ADMM) in digital in-line holographic microscopy) combines speckled illumination and ADMM-based computations for SR. By incorporating sparsity-based regularization, the system mitigates the speckle noise inherent in speckled illumination. The SRAD-DIHM system provides a threefold improvement in lateral resolution and a ninefold improvement in axial resolution over conventional DHM. The work effectively uses SRAD-DIHM for label-free imaging and metrology of nanoparticles.