Research Examples

Monitoring of apoptosis

Apoptosis induced by a cytopathic agent (bioactive phospholipids) in rat sarcoma cell observed with the Coherence-controlled holographic microscope (obj. 20x/NA 0.4). Pseudocolour quantitative phase images, time in minutes.

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Classification of cells by means of supervised machine learning

We proposed an approach for the classification of cellular morphologies by means of machine learning based on quantitative phase information gained by coherence-controlled holographic microscopy. Three types of cell morphologies induced by PBS were being distinguished. We compared our approach with the commonly used method based on morphometric features. The results imply that the quantitative phase features play important role in the classification. The methodology could be a valuable help in refining the monitoring of live cells in an automated fashion. The figure below shows morphological changes of LW13K2 cells induced by PBS. (a) Viable cells, (b) semi-deprived cells and (c) deprived cells.

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Scattering layer: Difference in image quality with the low and high coherence of illumination

Comparison of phase images of MCF-7 cells through turbid 0.1% biologically active phospholipids (BAPs) emulsion. CCHM equipped with (a) low-coherence illumination (halogen lamp), (b) coherent illumination without averaging (Fianium WhiteLase Supercontinuum laser), and (c) coherent illumination with the average of 10 frames. The advantage of low-coherence illumination for a single-shot image of cells is clearly demonstrated. Pseudocolour quantitative phase imaging (QPI), objectives 20 × ∕0.5.

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Cell reactions to biologically active phospholipids

A colony of human colorectal adenocarcinoma cells DLD-1 was followed in the static chamber after exposure to 0.15% BAPs in the culture medium. Three-hour intervals between (a) and (d) disclosed that apparent shrinkage of the whole colony began after 3 h, followed by degradation of some cells not only at the edge of the colony but also inside, with clear condensation of all cell bodies in the colony marking their death. Pseudocolour QPI, calibration bar expresses dry mass density in pg∕μm2, objectives 20 × ∕0.5.

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Cell cycle measurement

Left: Cell cycle measurement. Steady gain on the weight of mother (M) and first (D1, D2) and second (D3, D4) generation of daughter cells indicates continuous cell cycling. Right: The boxplot indicates Doubling Time of cells exposed to different nutritional conditions: full medium (FBS 10%) or basic serum-free (FBS 0%). Doubling Time is calculated from the growth rate of each cell for estimation of time that a cell potentially needs for doubling its mass and thus presumably finishing the cell cycle. The graph demonstrates a higher growth rate and consequently shorter cell cycle in full medium. Dot markers in boxes indicate mean, centreline is median, top of the box is 25th and bottom 75th percentile line, whiskers indicate 5th and 95th percentiles, outliers are plotted, 47 samples from each culture, significance was tested using unpaired t-test (***: p<0.001). 


Quantitative 3D Phase Imaging of Plasmonic Metasurfaces

Coherence-controlled holographic microscopy (CCHM) is a real-time, wide-field, and quantitative light-microscopy technique enabling 3D imaging of electromagnetic fields, providing complete information about both their intensity and phase. These attributes make CCHM a promising candidate for performance assessment of phase-altering metasurfaces, a new class of artificial materials that allow to manipulate the wavefront of passing light and thus provide unprecedented functionalities in optics and nanophotonics. We report on our investigation of phase imaging of plasmonic metasurfaces using holographic microscopy. 

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Polarization sensitive phase-shifting Mirau interferometry using a liquid crystal variable retarder

(a) Schema of the polarization adapted phase-shifting (P-S) Mirau interferometer. The P-S is based on a liquid crystal light modulation, imposed on an unaffected reference wave by the Liquid Crystal Variable Retarder (LCVR). (b-e) Experimental testing of the polarization adapted Mirau interferometer. (b) Phase reconstruction of the array of microlenses, (c) 3D illustration of the unwrapped phase, (d) height profiles across the valleys of the microlenses (Sections A and B), (e) height profiles across the tops of the microlenses (Sections C and D).

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Aberration resistant axial localization using a self-imaging of vortices

(a) Experimental setup for aberration resistant axial localization by the rotating Double-Helix Point Spread Function (DH PSF). (b) Rotating imaging of polystyrene beads, 1 micrometre in diameter, suspended in glass capillary tube. (c-e) Rotating images of polystyrene beads in magnified portions of the entire field of view (b). 

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Multimode fiber: Light-sheet microscopy at the tip of a needle

(a) A simplified scheme of the LS delivery using the MMF. The insets (I–VI) show the yz-plane profiles of the GB, BB and SI-BB LS in focus (x = 50 μm from fibre facet; LS scanning shown in Media. 1–3) and out of focus (x = 100 μm from fibre facet; LS scanning shown in Media. 4–6). (b) A strategy for obtaining the SLM hologram generating the GB LS at the fiber output. (c) A procedure converting the GB LS to a BB/SI-BB LS.

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