Digital holographic microscopy: a quantitative label-free microscopy technique for phenotypic screening.

Digital Holographic Microscopy (DHM) is a label-free imaging technique allowing visualization of transparent cells with classical imaging cell culture plates. The quantitative DHM phase contrast image provided is related both to the intracellular refractive index and to cell thickness. DHM is able to distinguish cellular morphological changes on two representative cell lines (HeLa and H9c2) when treated with doxorubicin and chloroquine, two cytotoxic compounds yielding distinct phenotypes.

Endoscopic low-coherence topography measurement for upper airways and hollow samples.

To evaluate the severity of airway pathologies, quantitative dimensioning of airways is of utmost importance. Endoscopic vision gives a projective image and thus no true scaling information can be directly deduced from it. In this article, an approach based on an interferometric setup, a low-coherence laser source and a standard rigid endoscope is presented, and applied to hollow samples measurements.

Label-free second-harmonic phase imaging of biological specimen by digital holographic microscopy.

We have previously developed a new way for nonscanning second-harmonic generation (SHG) microscopy [Opt. Lett. 34, 2450 (2009)].

Real time, nanometric 3D-tracking of nanoparticles made possible by second harmonic generation digital holographic microscopy.

In the past decade, quantitative phase imaging gave a new dimension to optical microscopy, and the recent extension of digital holography techniques to nonlinear microscopy appears very promising, for the phase of nonlinear signal provides additional information, inaccessible to incoherent imaging schemes. In this work, we show that the position of second harmonic generation (SHG) emitters can be determined from their respective phase, at the nanometer scale, with single-shot off-axis digital holography, making possible real-time nanometric 3D-tracking of SHG emitters such as nanoparticles.

Sub-Rayleigh resolution by phase imaging.

We report the experimental observation of systematically occurring phase singularities in coherent imaging of sub-Rayleigh distanced objects. A theory that relates the observation to the sub-Rayleigh distance is presented and compared with experimental measurements. As a consequence, the limit of resolution with coherent illumination is extended by a factor of 1.

Digital holographic microscopy investigation of second harmonic generated at a glass/air interface.

Optical second-harmonic generation, thanks to its coherent nature, is a suitable signal for interferometric measurements such as digital holography, a well-established imaging technique that allows recovery of complex diffraction wave fields from which it is possible to extract both amplitude-contrast and quantitative phase images. Here, we report on a multifunctional form of microscopy, namely, second-harmonic generation digital holographic microscopy. As a proof of concept, we have investigated the second-harmonic signal generated at the glass/air interface of a microscope slide under focused femtosecond laser illumination, and we propose, for the first time to our knowledge, a representation and interpretation of the recovered phase.