Conference Agenda

While scattered light conveys most of the information we perceive, scattering may also distort that information before it reaches our detectors. The problem is acute in many applications, such as in high-resolution microscopy of biological tissue, where scattering degrades both resolution and signal-to-noise ratio. Here, for the first time, we demonstrate that uniting two intrinsic properties of scattered light: speckle statistics and the angular memory effect, with highly non-linear optical response yields, rather surprisingly, super-resolution, low-background, non-invasive imaging of objects completely hidden behind a strongly scattering, opaque layer. Crucially, our technique of non-invasive imaging through scatterers does not resort to wavefront shaping, adaptive optics, complicated optical setups, or iterative image reconstruction algorithms. Because the strategy relies solely on the properties of scattered light and high-order nonlinear response of the fluorophores, it can be applied to any speckle-forming propagation, from biological tissue to multicore fibres, combined with any type of phenomenon that exhibits a sufficiently high order nonlinearity.

The functional properties of collagen arise from its molecular-scale organization and structural order at fibril and fiber levels. Detecting subtle changes in this organization requires imaging strategies capable of bridging contrast mechanisms across multiple spatial scales. In this work, we present a correlative framework that combines far-field and near-field optical methods to evaluate changes occurring in collagen fibrils under thermal- and oxidative stres-induced denaturation. Polarization-resolved second harmonic generation microscopy, scattering-type scanning near-field optical microscopy, accompanied by atomic force microscopy, are used to extract complementary structural and optical features of individual collagen fibrils.

We report a compact system for three-photon microscopy based on a hydrogen-filled hollow-core fiber pumped by a Ytterbium oscillator. We obtain 38 fs pulses at 1300 nm with efficiencies exceeding 34%, peak powers in the few MW range, and a well-defined linear polarisation. Subsequently, we combine the source with an endoscope based on a hollow-core fiber for three-photon imaging.

Imaging Flow Cytometry (IFC) combines high-throughput

analysis of individual cells with morphological characterization, but remains

limited by the fact that measurements yield two-dimensional images of

inherently three-dimensional structures. Herein, we propose a hybrid

optofluidic platform, combining a PDMS microfluidic system with a

reusable fused-silica optical module, that enables high-throughput 3D IFC.

A rotated microchannel geometry decouples illumination and detection

axes, enabling volumetric acquisition using light-sheet excitation. A

compact serpentine microchannel is used to inertially focus 15 µm particles

at velocities up to 1 m/s. The optical module, fabricated in fused silica by

femtosecond laser micromachining, employs orthogonal cylindrical lenses

to achieve diffraction-limited light-sheet generation. Experimental results

demonstrate efficient particle focusing and a light-sheet thickness below

2µm, in agreement with simulations.

Light sensitive nature of the imaging specimens is a general issue in bio-imaging. Slow z-scanning in typical 3D microscopy aggravates the problem of photobleaching and phototoxicity. High-speed 3D imaging techniques to observe fast and complex biological processes within thick, living specimens are need of the hour. Light field microscopy (LFM) and Extended depth of field microscopy (EDoF) can offer scanning-free imaging capable of recording volumetric images in a single snapshot, ideal for capturing live dynamics of biological specimens. The present work focuses on the realization of such high-speed volumetric imaging techniques in a single modular setup for sequential multi-colour fluorescence imaging.