In this article we present a complete laser scanning microscope designed for simultaneous spectral and lifetime measurements from every point of the specimen located within the field of view. The pulsed laser source used for two-photon excitation provides good spatial resolution with minimal invasivity. In addition, the detection module was optimized for minimal photon loss, allowing laser power minimization and further reduction of cells photodamage. Analysis of biological samples illustrates the performances of this configuration, particularly when applied to fluorescent resonance energy transfer (FRET) measurements. Indeed, multiparametric acquisition is particularly useful to discriminate between FRET and artifactual response due to acquisition invasivity or cell heterogeneity. Combined with adapted homemade driving software, this system is stable, portable, and optimized for living cell studies.

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