Coherence-controlled holographic microscopy enabled recognition of necrosis as the mechanism of cancer cells death after exposure to cytopathic turbid emulsion.

Coherence-controlled holographic microscopy (CCHM) in low-coherence mode possesses a pronounced coherence gate effect. This offers an option to investigate the details of cellular events leading to cell death caused by cytopathic turbid emulsions. CCHM capacity was first assessed in model situations that showed clear images obtained with low coherence of illumination but not with high coherence of illumination. Then, the form of death of human cancer cells induced by treatment with biologically active phospholipids (BAPs) preparation was investigated. The observed overall retraction of cell colony was apparently caused by the release of cell-to-substratum contacts. This was followed by the accumulation of granules decorating the nuclear membrane. Then, the occurrence of nuclear membrane indentations signaled the start of damage to the integrity of the cell nucleus. In the final stage, cells shrunk and disintegrated. This indicated that BAPs cause cell death by necrosis and not apoptosis. An intriguing option of checking the fate of cancer cells caused by the anticipated cooperative effect after adding another tested substance sodium dichloroacetate to turbid emulsion is discussed on grounds of pilot experiments. Such observations should reveal the impact and mechanism of action of the interacting drugs on cell behavior and fate that would otherwise remain hidden in turbid milieu.

Coherence-controlled holographic microscopy in diffuse media.

Low-coherence interferometric microscopy (LCIM) enables to image through scattering media by filtration of ballistic light from diffuse light. The filtration mechanism is called coherence gating. We show that coherence-controlled holographic microscope (CCHM), which belongs to LCIM, enables to image through scattering media not only with ballistic light but also with diffuse light. The theoretical model was created which derives the point spread function of CCHM for imaging through diffuse media both with ballistic and diffuse light. The results of the theoretical model were compared to the experimental results. In the experiment the resolution chart covered by a ground glass was imaged. The experimental results are in the good agreement with the theoretical results. It was shown both by experiments and the theoretical model, that with ballistic and diffuse light we can obtain images with diffraction limited resolution.

Numerical refocusing in digital holographic microscopy with extended-sources illumination.

Numerical refocusing can be seen as a method of compensating the defocus aberration based on deconvolution by inverse filtering [1] in digital holographic microscopy (DHM). It is well-understood in cases when a coherent (ie point and monochromatic) light source such as a collimated laser beam is used [2]. This paper extends the theory to the case of illumination by a quasi-monochromatic extended (spatially incoherent) source. Refocusing methods for spatially incoherent illumination are derived and benefits of this type of illumination are demonstrated. We have proved both theoretically and experimentally that coherent-based refocusing gives incorrect results for extended-source illumination, while results obtained using the newly derived method are correct.