Christian Depeursinge

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The spatially resolved reflectance of turbid media is studied at short source–detector separations (approximately one transport mean free path) with Monte Carlo simulations. For such distances we found that the first and second moments of the phase function play a significant role in the reflectance curve, whereas the effect of higher-order moments is weak. Second-order similarity relations are tested and are found efficient at reducing the number of relevant parameters necessary to predict the reflectance.

We present a digital method for holographic microscopy involving a CCD camera as a recording device. Off-axis holograms recorded with a magnified image of microscopic objects are numerically reconstructed in amplitude and phase by calculation of scalar diffraction in the Fresnel approximation. For phase-contrast imaging the reconstruction method involves the computation of a digital replica of the reference wave. A digital method for the correction of the phase aberrations is presented. We present a detaile

Digital Holographic Microscopy (DHM) provides three-dimensional (3D) images with a high vertical accuracy in the nanometer range and a diffracted limited transverse resolution. This paper focuses on 3 different tomographic applications based on DHM. First, we show that DHM can be combined with time gating: a series of holograms is acquired at different depths by varying the reference path length, providing after reconstruction images of slices at different depths in the specimen thanks to the short coherenc

We have employed femtosecond laser writing in order to induce refractive-index changes and waveguides in Ti3+-doped sapphire. Doping the sapphire crystal with an appropriate ion significantly reduces the threshold for creating structural changes, thus enabling the writing of waveguide structures. Passive and active buried channel waveguiding is demonstrated and images of the guided modes, propagation-loss values, fluorescence spectra, and output efficiencies are presented. The guiding area is located around

Quantitative Phase Imaging techniques such as DHM have emerged recently in life sciences and can be aimed at monitoring and quantifying non-invasively dynamic cellular processes modifying cell morphology and/or content. Concretely, the DHM phase signal depends on two cell parameters: cell thickness and integral refractive index. Consequently, due to its dual origin, the interpretation of the phase signal variations remain difficult. Since a net water flux across the cell membrane causes a variation of both

Different interferometric techniques were developed last decade to obtain full field, quantitative, and absolute phase imaging, such as phase-shifting, Fourier phase microscopy, Hilbert phase microscopy or digital holographic microscopy (DHM). Although, these techniques are very similar, DHM combines several advantages. In contrast, to phase shifting, DHM is indeed capable of single-shot hologram recording allowing a real-time absolute phase imaging. On the other hand, unlike to Fourier phase or Hilbert pha

Digital holographic microscopy is an interferometric technique enabling the measurement of the quantitative phase shifts induced by cell bodies. We correlate the phase signal measured on neurons with calcium imaging measured by fluorescence on cells loaded with Fluo-4, to monitor responses to glutamate challenges, which provoke well-known calcium increases through activation of various membrane receptors. A very good correspondence can be identified between the two signals, showing the links between the pha

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 recovering complex diffraction wavefields from which it i ...

A holographic setup that involves the use of a multicore optical fiber as an in situ recording medium has been developed. The hologram is transmitted to a CCD camera for electronic processing, and the image is reconstructed numerically, providing more flexibility to the holographic process. The performances of this imaging system have been evaluated in terms of the resolution limit and robustness relative to noise. The experimental cutoff frequency has been measured experimentally over a range of observatio

A new holographic technique based on a numerical reconstruction method is presented and applied to endoscopic holograms. The hologram is obtained by the interference between the light reflected by the object and a reference beam taken as a plane wave travelling back along the axis of the multimode fiber bundle (MMB). The reconstruction of the image is computed numerically, using a fast algorithm to perform the Fresnel transform of the illuminated hologram. The quality of the reconstructed image has been eva

In this paper, we present a transmission polarization digital holographic microscope (Pol-DHM) that allows for imaging the state of polarization of a wave front with the acquisition of a single hologram. This apparatus records, using a CCD camera, the interference in off-axis geometry between two orthogonally polarized reference waves and an object wave transmitted through a microscopic sample and magnified by a microscope objective. Since the reference waves have orthogonal polarizations, they do not inter

We report on a numerical method for the reconstruction of wavefronts in Digital Holographic Microscopy (DHM). It yields simultaneous amplitude and quantitative phase contrast imaging by acquiring a single hologram. The reconstruction method computes the propagation of the complex optical wavefront diffracted by the object and is used to determine the refractive index and/or shape of the object with accuracies in the nanometer range along the optical axis. The technique comprises the recording of a digital h

With the recent technological advances, there is an increasing need for measurement systems providing interferometer resolution for inspection of large quantities of individual samples in manufacturing environments.. Such applications require high measurement rates, robustness, ease of use, and non-contact systems. We show here that Digital Holographic Microscopy (DIM), a new method that implements digitally the principle of holography, is particularly well suited for such industrial applications. With the

Local and superficial near-infrared (NIR) optical-property characterization of turbid biological tissues can be achieved by measurement of spatially resolved diffuse reflectance at small source–detector separations (

For holographic biopsy purposes, holograms of biological tissue samples have been recorded in vitro to establish the possibility of differentiating tissues on the holograms. With the use of specific absorbing dyes for staining tissues, the contrast has been improved. On the holograms, tissue architecture has been observed in the cortex of the kidney. Isolated epithelial cells could be seen with a distinct nucleus. Two distinct layers of the gray matter in the human brain have been differentiated. Finally, t

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 base ...

We propose a Riesz transform approach to the demodulation of digital holograms. The Riesz transform is a higher-dimensional extension of the Hilbert transform and is steerable to a desired orientation. Accurate demodulation of the hologram requires a relia ...

Digital holographic microscopy (DHM) allows optical-path-difference (OPD) measurements with nanometric accuracy. OPD induced by transparent cells depends on both the refractive index (RI) of cells and their morphology. This Letter presents a dual-wavelengt ...

We demonstrate the use of digital holographic microscopy (DHM) as a metrological tool in micro-optics testing. Measurement principles are compared with those performed with Twyman-Green, Mach-Zehnder, and white-light interferometers. Measurements performed ...

We describe here a numerical application of the optical low- coherence holographic microscopy (OLCHM) technique. A low coherent source illuminates an object and the backscattered light interfere with a reference wave which optical path's length can be precisely adjusted. Holograms are recorded by a CCD camera and numerically reconstructed. With this technique optical tomography can be performed with a single scan along the optical axis. The transverse resolution of the reconstructed images mainly depends on

Christian Depeursinge

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Monte Carlo study of diffuse reflectance at source-detector separations close to one transport mean free path

Simultaneous amplitude-contrast and quantitative phase-contrast microscopy by numerical reconstruction of Fresnel off-axis holograms

Use of digital holographic microscopy in tomography

Femtosecond-irradiation-induced refractive-index changes and channel waveguiding in bulk Ti3+: Sapphire

Dual-wavelength Digital Holography for quantification of cell volume and integral refractive index (RI)

Advantages of digital holographic microscopy for real-time full field absolute phase imaging

Cell death detection and ionic homeostasis monitoring with digital holographic microscopy

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

Performances of endoscopic holography with a multicore optical fiber

Performance of on-axis holography with a flexible endoscope

Polarization digital holographic microscope: A single acquisition for a complete determination of polarization state

3D imaging of surfaces and cells by numerical reconstruction of wavefronts in Digital Holography applied to transmission and reflection microscopy

Digital Holography Microscopy (DHM): Fast and robust systems for industrial inspection with interferometer resolution

In Vivo Local Determination of Tissue Optical Properties: Applications to Human Brain

High-resolution holography and biopsy: Preliminary results

Endoscopic low coherence topography measurement for upper airways and hollow samples

Local demodulation of holograms using the Riesz transform with application to microscopy

Simultaneous cell morphometry and refractive index measurement with dual- wavelength digital holographic microscopy and dye-enhanced dispersion of perfusion medium

Characterization of microlenses by digital holographic microscopy

Optical tomography at the microscopic scale by means of a numerical low coherence holographic technique