Toward 3D imaging of femtosecond laser filament in air by a CCD within a single exposure

(1)We experimentally demonstrated the 3D propagation of laser filament in air by an F-P cavity assisted imaging within a single exposure. The cross-sectional intensity patterns at different longitudinal positions along filament within a single exposure of CCD were recorded.In previous imaging systems, it is generally necessary to move the imaging lens and CCD step by step so that to obtain multiple cross-sections of the object of the filament. (2)The intensity evolution along laser filament by the F-P cavity assisted imaging method was consistent with the filament fluorescence measurement from the side. This illustrates the usability of this imaging method. (3)As an application, the transition of laser propagation from linear to nonlinear was unveiled by the F-P cavity assisted 3D imaging. (4)Although the F-P cavity assisted 3D imaging in a single exposure was demonstrated at 1030nm femtosecond laser for filamentation, this imaging method does in principle work for 3D propagation characterization of other wavelength lasers and their accompanying radiations which is in particular useful to record the propagation of structured light within a single exposure.