Fast2P – A fast and a large-field two-photon light- sheet platform for functional and anatomical imaging

Light-sheet (LS) microscopy has recently emerged as a powerful alternative to confocal or two-photon (2P) epifluorescence techniques for volumetric fluorescence imaging of biological systems. More recently, two-photon implementations of LS microscopes were introduced.

The use of an infra-red source offers several advantages: (i) it mitigates the detrimental effects of light-scattering by biological tissues, (ii) for in vivo functional imaging applications, it prevents interference of the imaging beam with the visual system of the animal, (iii) it maintains high axial resolution over extended fields of view when combined with Bessel-beam shaping.

However, the low efficiency of two-photon excitation effectively reduces the imaging speed of 2P-LS microscopy by ~10 fold as compared to one-photon LS microscopy. This limitation is essentially associated with the available power offered by the standard femto-second infrared sources, such as Ti:Sapphire lasers.

In recent years, a new generation of regenerative amplifiers has been developed, with much lower repetition rate but similar mean power. As the 2P effect depends quadratically on the laser intensity, these lasers offer increased fluorescence signals.

This project, aims at harnessing the power provided by a new generation of femtosecond infrared lasers to develop a dual two-photon light-sheet imaging (2P-LS) platform with unmatched performances. The first system (2P) will provide unprecedented imaging speed, and will be used for ultra-fast volumetric ​in vivo functional imaging and monitoring of fast physiological processes. The second system (LS) will enable large volume, high-resolution imaging, and will be used for ​in toto structural imaging of clarified brains.

The performances of this dual microscope, developed at the Laboratoire Jean Perrin, will be validated on 6 applicative projects provided by the teams forming the consortium. The technology will then be transferred to the LUMIC network of imaging platforms to be made readily accessible to the biology community in Ile-de-France region.

Our final goal is to offer a commercial version through an industrial partnership with Phase View SARL (Verrières-le-Buisson, Essonne, Ile-de-France).