Horiba Jobin Yvon Sas

Frederic Desserouer

A Dyson imaging spectrometer includes an entry port extending in a direction X, an exit port, a diffraction grating including a set of lines on a concave support, an optical system including a lens, the lens including a plane first face and a convex second face, the convex face of the lens and the concave face of the diffraction grating being concentric, the optical system being adapted to receive an incident light beam coming from the entry port and to direct it toward the diffraction grating, to receive a beam diffracted by the diffraction grating, and to form a spectral image of the diffracted beam in a plane of the exit port, the spectral image being adapted to be spatially resolved in an extension direction X' of the image of the entry port. The diffraction grating includes a set of non-parallel and non-equidistant lines and/or the support of diffraction grating is aspherical in order to form an image of the entry port in the exit plane of improved image quality and of very low distortion.

Dyson-type imaging spectrometer having improved image quality and low distortion

A reflection metal diffraction grating has a high diffraction efficiency for diffracting femtosecond mode laser pulses, and includes a substrate with a set of lines having a pitch A. The substrate is made of metal or covered with a metal layer, and the grating includes a thin film of dielectric material having a thickness, the dielectric film covering the metal surface of the lines of the grating, the grating being suitable for receiving a pulsed electromagnetic lightwave in a femtosecond mode. The thickness of the dielectric thin film is lower than 50 nm, and is suitable for reducing by a third order factor at least the maximum of the square of the electric field of the electromagnetic lightwave on the metal surface and in the metal layer of the substrate as compared to the square of the electric field at the surface of a metal grating not having a dielectric thin film.

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Palaiseau, France

Frederic Desserouer