Living specimen tomography by digital holographic microscopy: morphometry of testate amoeba

This paper presents an optical diffraction tomography technique based on digital holographic microscopy. Quantitative 2-dimensional phase images are acquired for regularly-spaced angular positions of the specimen covering a total angle of π, allowing to built 3-dimensional quantitative refractive index distributions by an inverse Radon transform. A 20x magnification allows a resolution better than 3 μm in all three dimensions, with accuracy better than 0.01 for the refractive index measurements. This technique is for the first time to our knowledge applied to living specimen (testate amoeba, Protista). Morphometric measurements are extracted from the tomographic reconstructions, showing that the commonly used method for testate amoeba biovolume evaluation leads to systematic under evaluations by about 50%

Apparatus and method for quantitative phase tomography through linear scanning with coherent and non-coherent detection

The disclosed invention describes a new apparatus performing a new data acquisition for quantitative refractive index tomography. It is based on a linear scanning of the specimen, opposed to the classical approaches based on rotations of either the sample or the illumination beam, which are based on the illumination with plane waves, which orientation is successively modified in order to acquire angular information. On the contrary, the inventive apparatus and method rely on a specially shaped illumination, which provides straightforwardly an angular distribution in the illumination of the specimen. The specimen can thus be linearly scanned in the object plane in order to acquire the data set enabling tomographic reconstruction, where the different positions directly possess the information on various angles for the incoming wave vectors

Histoire de la maison de Lvxembovrg, ov sont plvsievrs occvrrences de guerres & affaires, tant d'Afrique & d'Asie que d'Europe /

Illustrée de notes. Avec une continuation jusques à présent [par N. G. Pavillon] et en fin les tables généalogiques des princes de cette illustre maison... avec les blasons de leurs armes ...Europeana-GoogleBook

Complex index refraction tomography with sub ?/6-resolution

The present invention discloses a method to improve the image resolution of a microscope. This improvement is based on the mathematical processing of the complex field computed from the measurements with a microscope of the wave emitted or scattered by the specimen. This wave is, in a preferred embodiment, electromagnetic or optical for an optical microscope, but can be also of different kind like acoustical or matter waves. The disclosed invention makes use of the quantitative phase microscopy techniques known in the sate of the art or to be invented. In a preferred embodiment, the complex field provided by Digital Holographic Microscopy (DHM), but any kind of microscopy derived from quantitative phase microscopy: modified DIC, Shack- Hartmann wavefront analyzer or any analyzer derived from a similar principle, such as multi-level lateral shearing interferometers or common-path interferometers, or devices that convert stacks of intensity images (transport if intensity techniques: TIT) into quantitative phase image can be used, provided that they deliver a comprehensive measure of the complex scattered wavefield. The hereby-disclosed method delivers superresolution microscopic images of the specimen, i.e. images with a resolution beyond the Rayleigh limit of the microscope. It is shown that the limit of resolution with coherent illumination can be improved by a factor of 6 at least. It is taught that the gain in resolution arises from the mathematical digital processing of the phase as well as of the amplitude of the complex field scattered by the observed specimen. In a first embodiment, the invention teaches how the experimental observation of systematically occurring phase singularities in phase imaging of sub-Rayleigh distanced objects can be exploited to relate the locus of the phase singularities to the sub-Rayleigh distance of point sources, not resolved in usual diffraction limited microscopy. In a second, preferred imbodiment, the disclosed method teaches how the image resolution is improved by complex deconvolution. Accessing the object's scattered complex field - containing the information coded in the phase - and deconvolving it with the reconstructed complex transfer function (CTF) is at the basis of the disclosed method. In a third, preferred imbodiment, it is taught how the concept of "Synthetic Coherent Transfer Function" (SCTF), based on Debye scalar or Vector model includes experimental parameters of MO and how the experimental Amplitude Point Spread Functions (APSF) are used for the SCTF determination. It is also taught how to derive APSF from the measurement of the complex field scattered by a nanohole in a metallic film. In a fourth imbodiment, the invention teaches how the limit of resolution can be extended to a limit of ?/6 or smaller based angular scanning. In a fifth imbodiment, the invention teaches how the presented method can generalized to a tomographic approach that ultimately results in super-resolved 3D refractive index reconstruction

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 recovering complex diffraction wavefields from which it is possible to extract both amplitude- contrast and quantitative phase images. Here, we report on a new, multi-functional form of microscopy: 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 propose for the first time a representation and interpretation of the recovered phase. In this simple, yet very educative case study, we observe that the second harmonic is generated by the axial component of the incident field polarizatio

Off-axis low coherence interferometry contouring

In this article we present a method to achieve tri-dimensional contouring of macroscopic objects. A modified reference wave speckle interferometer is used in conjunction with a source of reduced coherence. The depth signal is given by the envelope of the interference signal, directly determined by the coherence length of the source. Fringes are detected in the interferogram obtained by a single shot and are detected by means of adequate filtering. With the approach based on off-axis configuration, a contour line can be extracted from a single acquisition, thus allowing to use the system in harsh environment. (C) 2009 Elsevier B.V. All rights reserved

Second Harmonic and Fundamental Wavelength Digital Holographic Microscopy

We report on a new, multi-functional second harmonic generation digital holographic microscope that allows retrieval of an object complex diffraction wavefront at both second harmonic and fundamental wavelengths