Multi-harmonic structured illumination-based optical diffraction tomography

Abstract

Imaging speed and spatial resolution are key factors in optical diffraction tomography (ODT), while they are mutually exclusive in 3D refractive index imaging. This paper presents a multi-harmonic structured illumination-based optical diffraction tomography (MHSI-ODT) to acquire 3D refractive index (RI) maps of transparent samples. MHSI-ODT utilizes a digital micromirror device (DMD) to generate structured illumination containing multiple harmonics. For each structured illumination orientation, four spherical spectral crowns are solved from five phase-shifted holograms, meaning that the acquisition of each spectral crown costs 1.25 raw images. Compared to conventional SI-ODT, which retrieves two spectral crowns from three phase-shifted raw images, MHSI-ODT enhances the imaging speed by 16.7% in 3D RI imaging. Meanwhile, MHSI-ODT exploits both the 1st-order and the 2nd-order harmonics; therefore, it has a better intensity utilization of structured illumination. We demonstrated the performance of MHSI-ODT by rendering the 3D RI distributions of 5 µm polystyrene (PS) microspheres and biological samples.

Recent Advances and Current Trends in Transmission Tomographic Diffraction Microscopy

“…The high-resolution tomographic microscopes developed by Tomocube, Inc. [ 39 ], exploit the benefit of this approach. The concept of structured illumination has also been adapted to tomographic microscopy [ 90 , 99 , 100 ]. Note, however, that structured illumination diffraction tomography relies on a linear process with respect to field amplitude, while fluorescence structured illumination microscopy relies on a quadratic process with respect to field amplitude; thus, the underlying image formation processes are fundamentally different [ 101 ].…”