Centre National De La Recherche Scientifique

Université De Lille

Centrale Lille Institut

Junia

I-sen, Inc.

Menapic

Universite De Lille 1

Centre National De La Recherche Scientifique-cnrs

Université Des Sciences Et Technologies De Lille 1

Groupe Hei Isa Isen

Arnaud Devos

Grégory Caruyer

Patrick Emery

Arnaud Le Louarn

Sabrina Sadtler

A phonon parametric oscillator is provided. The phonon parametric oscillator comprises a laser for periodically emitting brief optical pulses (IL), an assembly for generating acoustic pulses (IA) and a medium for coupling the acoustic pulses to an object (O), the assembly for generating acoustic pulses comprising an entrance face, an exit face, a conversion medium for converting the brief optical pulses into acoustic pulses and a propagation medium for propagating said acoustic pulses, the entrance and exit faces being reflective to the acoustic pulses, the propagation medium having a defined thickness, the exit face making contact with the coupling medium. In the phonon parametric oscillator according to the invention, the round-trip time of an acoustic pulse due to reflection from the entrance and exit faces, is equal to the emission period (τ) of the laser, so that the reflected acoustic pulse is in phase with the following acoustic pulse.

Phonon parametric oscillator

A method refocuses on an optical assembly target surface, using at least one beam originating from a short-pulse optical source, having at least one optical system for focusing the beam on the surface. Refocusing occurs after learning reference conditions for which the assembly is considered as focused. A focusing signal is detected representing a time overlap of pulses between a beam reflected and a reference beam not reflected by the surface, one of the beams delayed by a delay line. The optical path on which the delay line is placed is varied, on the basis of the reference conditions, to cause the focusing signal to reach or exceed a predetermined threshold. The focus is adjusted on the basis of the path variation between the reference conditions and the conditions for which the focusing signal reaches or exceeds the threshold.

Method for refocusing an optical assembly

The present invention relates to a device () for characterizing an interface of a structure (), said structure () comprising a solid first material and a second material, the materials being separated by said interface. The device () comprises: The invention also relates to a corresponding method of characterization.

Device for characterizing an interface of a structure and corresponding device

The invention relates to a structure characterising device comprising means which are used for generating a first pump radiation and a second probe radiation and for transmitting different wavelength radiation, means for producing a time offset between said first pump and second probe radiation on the structure by means of detecting means of said second beam after the reflection or transmission thereof to said structure in such a way that an analysis signal is generated, means for processing said signal and identifying an area corresponding to the signal jump, for determining the jump amplitude according to different wavelengths, for comparing said amplitude with a theoretical amplitude variation pattern according to the wavelengths and for determining, for the wavelength characteristic for said theoretical pattern, a characteristic value associated to the structure thickness and to the radiation propagation velocity in said structure.

Method and device for characterising a structure by wavelength effect in a photoacoustic system

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Ennetieres en Weppes, France

Arnaud Devos