Centre National De La Recherche Scientifique

Commissariat &#xc0; L'&#xc9;nergie Atomique Et Aux &#xc9;nergies Alternatives

Sorbonne Université

Université De Paris

Institut National De La Sante Et De La Recherche Medicale

Université Pierre Et Marie Curie (paris 6)

Ecole Polytechnique

Université Pierre Et Marie Curie

Universite Paris Cité

Gilles Tessier

Sylvain Gigan

Marc Guillon

Pascal Berto

Arnaud Verdant

Antoine Dupret

Yannick De Wilde

Jean-Paul Roger

Christine Boue

Lèo Greusard

Mihaela Streza

François Ramaz

Samuel Gresillon

Tengfei Wu

Kamel Bencheikh

Dimitris Papadopoulos

Timothé Laforest

A method for determining wavefront shapes of a multi-spectral signal light beam from a single signal image acquisition of said multi-spectral signal beam, with a device including an optical assembly made at least of an optical mask and an imaging sensor, notably a matrix imaging sensor, for generating and recording intensity patterns of incident beams, by having these beams reflect on, or propagate through, the optical mask. The optical mask having the optical properties: i) to cause the intensity pattern to depend on the wavefront shape, so that a tilt applied to the wavefront shape results in a displacement amount of the intensity pattern, and ii) to produce uncorrelated intensity patterns over at least one surface area A of the imaging sensor, for a plurality of respective incident monochrome beams of different wavelengths having a same wavefront shape.

Wavefront sensors and wavefront shape determination using related imaging sensors

A method for determining wavefront shapes of N angular channels Cof different propagation directions P, said propagation directions Pbeing determined by a mean propagation direction vector, from a single signal image acquisition I(x,y) of a multi-angular signal light beam containing said angular channels, each angular channel Ci being separated from other angular channels Cj by an angular separation &#x394;&#x3b1;defined by &#x394;&#x3b1;=arccos, where '&#xb7;' stands for the inner product betweenand.

Method for measuring several wavefronts incoming from different propagation directions

An optical detection device includes a light source emitting a light beam whose electromagnetic field, a means adapted to divide the beam into a first beam defining a first reference pathway and a second beam defining a second sample pathway, a modulation system frequency-shifting the electromagnetic fields of the two beams, a beam coupler adapted to collect the beams, an optical detection system adapted to detect the signal arising from the interference between the beams and coupled via the coupler, the sample being placed in the sample pathway, the optical detection system comprising an optical detector and a device adapted to measure the amplitude and the phase of the signal, an opaque screen comprising an optical aperture is placed at the level of a zone of a sample, in proximity to the sample, in the sample pathway.

SNOM device using heterodyne detection

The invention relates to a method for assessing the depth of a crack near the surface of a material, characterized in that said method includes the following steps: heating an area located near the crack using of a heat source () that is periodically modulatable into a heat flow at a controllable frequency, a so-called 'modulation frequency', varying the frequency so as to vary the heat diffusion length between an initial value, less than the distance between the heated area and the crack, and a final value that is greater than the distance between the heated area and the crack; determining the variation, depending on the heat diffusion length, in a function on the basis of at least one derivative, relative to a space variable, of the amplitude of the sinusoidal component of the temperature, on the surface of the material and at the modulation frequency, at each point of a set of points of the crack so as to cause a first area of variation in the function to appear, wherein said function increases at a first nonzero slope, followed by a second variation area, wherein said function increases at a second slope, different from the first slope; and assessing the depth of the crack on the basis of the value of the heat diffusion length at the intersection of the first variation area and the second variation area, the so-called 'intersection length'.

Method for assessing the depth of a crack

The invention concerns a system for measuring and controlling the wave-front of a coherent light beam (), comprising: a device for generating a reference light beam () that is coherent with said coherent light beam (); a partially reflective monolithic device () comprising an array of elementary cells, each elementary cell comprising at least one element () for measuring a portion of the incident wave interfering between the coherent light beam and the reference light beam and a phase modulation element () for modulating the phase of the reflected beam; and a control device () for controlling said phase modulation element making use of the information from the associated measuring element.

Device for measuring and controlling the wave-front of a coherent light beam

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Paris, France

Gilles Tessier