Construction of vector vortex beams on hybrid-order Poincaré sphere through highly scattering media.

Vector vortex beams (VVBs) have attracted extensive attention due to their unique properties and their wide applications in fields such as optical manipulation and optical imaging. However, the wavefronts of the vector vortex beams are highly scrambled when they encounter highly scattering media (HSM), such as thick biological tissues, which greatly prevents the applications of VVBs behind HSM. To address this issue, we propose a scheme to construct VVBs of freewill position on the surface of hybrid-order Poincaré sphere (HyOPS) through HSM. With the measurement of two orthogonal scalar transmission matrices, the conjugated wavefronts for constructing orbital angular momentum beams with arbitrary topological charge in right and left circularly polarized states through HSM can be calculated, respectively. When an input wavefront superimposed by the two conjugated wavefronts with an appropriate ratio and phase delay, impinges on the HSM, the desired VVB can be created through HSM. To demonstrate the viability of our scheme, a series of VVBs on different locations of various HyOPSs have been reconstructed through a ZnO scattering layer experimentally. Furthermore, to characterize the polarization distribution of the generated beams, the polarization maps of these beams are derived by measuring the four Stokes parameters, which agree well with the theoretical distributions. This work will promote the applications of VVBs in highly scattering environments.

Three-dimensional multi-color optical nanoscopy at sub-10-nm resolution based on small-molecule organic probes.

Achieving nanometer-scale resolution remains challenging in expansion microscopy due to photon loss. To address this concern, here we develop a multi-color expansion stimulated emission depletion technique based on small-molecule probes to realize high labeling density and intensity. Our method substantially lowers the barrier to visualizing diverse intracellular proteins and their interactions in three dimensions. It enables us to achieve sub-10-nm resolution in structures such as microfilaments, lysosomes, and mitochondria, providing new insights into cell biology.

High-speed spatially re-modulated structured illumination microscopy.

Structured illumination microscopy (SIM) allows non-invasive visualization of nanoscale subcellular structures. However, image acquisition and reconstruction become the bottleneck to further improve the imaging speed. Here, we propose a method to accelerate SIM imaging by combining the spatial re-modulation principle with Fourier domain filtering and using measured illumination patterns. This approach enables high-speed, high-quality imaging of dense subcellular structures using a conventional nine-frame SIM modality without phase estimation of the patterns. In addition, seven-frame SIM reconstruction and additional hardware acceleration further improve the imaging speed using our method. Furthermore, our method is also applicable to other spatially uncorrelated illumination patterns, such as distorted sinusoidal, multifocal, and speckle patterns.

Fast reconstruction algorithm for structured illumination microscopy.

Structured illumination microscopy (SIM) is a powerful technique for providing super-resolution imaging, but its reconstruction algorithm, i.e., linear reconstruction structured illumination microscopy (LRSIM) algorithm in the Fourier domain, limits the imaging speed due to its computational effort. Here, we present a novel reconstruction algorithm that can directly process SIM data in the spatial domain. Compared to LRSIM, this approach uses the same number of frames to achieve a comparable resolution but with a much faster processing speed. Our algorithm was verified on both simulated and experimental data using sinusoidal pattern illumination. Moreover, this algorithm is also applicable for speckle pattern illumination.