Conference Agenda

In the last decade, the spatial control and imaging of optical phase has profoundly transformed photonics, including microscopy. This talk presents two complementary contributions to this field. First, I will introduce a wavefront-shaping concept exploiting the thermo-optical effect to engineer light phase at the micro-scale, yielding reconfigurable, broadband, polarization-insensitive transmission-mode micro-components, with applications in 3D fluorescence microscopy. Second, I will show how complex media, such as diffusers, can encode optical wavefronts, providing a cost-effective route to quantitative phase imaging and, more importantly, a multiplexing capability for wavefronts with distinct incidence angles or wavelengths, opening new perspectives for multimodal biomedical imaging.

We present a compact lensless quantitative phase imaging (QPI) system for label-free, long-term monitoring of living cells directly inside a standard incubator. The proposed microscope employs an in-line transmission configuration without image focusing optics, recording diffraction patterns on a CMOS sensor, and reconstructing complex-valued object fields via iterative phase retrieval with complex-domain denoising. This architecture enables a mechanically robust, cost-effective platform with a large field of view suitable for parallel, time-lapse measurements. The system was validated using LN229 human glioblastoma cells under controlled incubator conditions over a 50-hour period, with imaging performed every 5 minutes. From reconstructed phase maps, both morphological descriptors (area, shape, circularity) and biophysical parameters (cellular dry mass and its temporal evolution) were extracted at single-cell resolution. The results demonstrate distinct dry-mass dynamics associated with different cell death pathways. Apoptosis is characterized by abrupt mass loss and morphological collapse, whereas necrosis exhibits gradual mass decrease without sharp transitions. Late-onset apoptosis shows delayed but rapid mass decline following stable growth.

These findings highlight the ability of lensless QPI to provide quantitative, label-free phenotyping of cell fate and stress response, offering a scalable alternative to conventional microscopy for drug testing, toxicity screening, and culture-quality monitoring.

Conventional high-performance benchtop microscopes rely on bulky and expensive hardware, complex illumination schemes, and multi-element optics, which limit their use outside laboratory environments, particularly in resource-limited and field settings. Here, we present a handheld smartphone-based microscope featuring a compact single-lens architecture and a sparse multi-annular illumination strategy based on Kramers-Kronig relations (sAIKK). By exploiting smartphone for programmable, NA-matched illumination without mechanical modulation, the proposed method enables efficient fourfold synthetic aperture quantitative phase imaging (QPI). Experimental validation on a resolution target demonstrates a resolution of 691 nm from four images, which is improved to 345 nm of 0.92 NA by incorporating two sparse annular illuminations. We further demonstrate the diagnostic and analytical capabilities of the prototype through on an unstained gastric fundus cross-section, morphometric analysis and screening of malaria-infected blood smears, and color imaging of a pine stem sample. By combining modular hardware with efficient sampling, this do-it-yourself and cost-effective platform provides an accessible alternative to high-end microscopes, with high potential for rapid on-site diagnostics, field deployment, and scientific education.

Optical microscopy remains a cornerstone of new biomedical discoveries because it enables high resolution observation of biological processes. However, it is fundamentally constrained by a limited imaging depth, typically ~ 100 μm, caused by light scattering in biological tissues. To overcome this barrier and enable deep tissue imaging, illumination wavefront shaping has emerged. However, advances in the wavefront shaping hardware, i.e., spatial light modulators (SLMs), are required to enable in vivo imaging demos. Here, we introduce photonic integrated circuits (PICs) as a platform for wavefront shaping, offering improvements in modulation speed, pixel pitch, and overall system compactness. We employ optical phased arrays (OPAs) with 128 antennas to perform wavefront phase modulation and achieve diffraction-limited focusing through static tissue-like samples. In addition, we conduct an experimental analysis of the OPA design space to identify optimal architectures for focusing in scattering media. For endoscopy applications, we demonstrate wavefront shaping through multimode fibers (MMFs), enabling focus raster scanning through a single fiber. This demonstration has strong potential for minimally invasive endoscopy in both neuroscience and clinical imaging since MMF’s diameter can be just 100 μm. The devices were fabricated on imec’s silicon nitride platform - relevant for microscopy due to its visible-light compatibility.

We report a compact transmission-mode wavefront shaping device based on thermo-optical actuators arrays. We propose a strategy to increase the actuator density, characterize and model their temporal dynamics and implement overdrive strategies to reduce response times. Finally, we demonstrate the device’s potential for light focusing through scattering media