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Very narrow band filters for the ultraviolet

As part of a research and technology (R&T) project funded by the Centre National d’Etudes Spatiales (CNES), the RCMO team is interested in the development of bandpass filters in the near ultraviolet for LIDAR applications. The objective of this project is to realize a very narrow band filter centered at 355 nm and presenting a uniform and high transmission over a spectral range of 0.1 nm with a rejection equal to OD5 at 0.5 nm on either side of the centering wavelength. The development of this type of components requires on the one hand a perfect control of the losses of the materials used (HfO2/SiO2) for the filter but also an extremely precise control of the thickness of each layer.

In a first phase, the RCMO team has developed, on the Bühler HELIOS machine deposition, parameters of materials compatible with the realization of a filter with the specified performances (T > 80%). A study on both the synthesis of the filters and on the optical monitoring techniques has allowed the demonstration of the first prototypes with performances close to the specified ones described above.

A new phase of the project is beginning and should eventually allow removing the last technological barriers and provide CNES with the first prototypes meeting the specifications.

Fundings: CNES

Contacts: Frédéric Lemarquis/Julien Lumeau